Closures for pivotal bone anchor assemblies having splay resisting thread forms

ABSTRACT

A pivotal bone anchor assembly for securing an elongate rod to a bone of a patient. The assembly includes a receiver having pair of upright arms that define an open channel configured to receive the elongate rod and a discontinuous helically wound receiver guide and advancement structure formed into the interior surfaces of the upright arms. The assembly further includes a closure configured for positioning within the open channel to secure the elongate rod to the receiver in a locked configuration, with the closure having an outer surface with a mating continuous helically wound closure guide and advancement structure configured to resist a tendency toward splaying between the upright arms upon a screwing in of the closure within the open channel by rotatable engagement with the receiver guide and advancement structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/987,741, filed Aug. 7, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/005,873, filed Jun. 12, 2018, now U.S. Pat. No.10,751,095, which is a continuation of U.S. patent application Ser. No.15/867,095, filed Jan. 10, 2018, now U.S. Pat. No. 9,999,452, which is acontinuation of U.S. patent application Ser. No. 14/043,139, filed Oct.1, 2013, now U.S. Pat. No. 10,039,577, which is a continuation of U.S.patent application Ser. No. 12/583,821, filed Aug. 26, 2009, now U.S.Pat. No. 8,591,515, which is a continuation of U.S. patent applicationSer. No. 10/996,349, filed Nov. 23, 2004, now U.S. Pat. No. 7,621,918,each of which is incorporated by reference in its entirety herein, andfor all purposes.

BACKGROUND OF THE INVENTION

The present invention relates to apparatuses and methods for use inperforming spinal surgery and, in particular, to tools and methods ofusing such tools, especially for percutaneously implanting spinal screwsand for implanting a rod for spinal support and alignment, usingminimally invasive techniques.

For many years, spinal osteosynthesis apparatuses have been utilized tocorrect spinal deformities, injuries or disease. In such procedures,elongate rods are surgically attached to vertebrae of the spine toprovide support and/or to realign or reposition certain vertebrae. Suchrods are secured to vertebrae utilizing bone screws and other spinalimplants. In order to reduce the impact of such surgery on the patient,a desirable approach is to insert such implants percutaneously or withsurgical techniques that are minimally invasive to the body of thepatient.

Problems arise when implantation tools designed for traditional surgerythat is highly invasive are utilized in percutaneous surgery. The toolsmay be bulky, oversized or have irregular surfaces or protrusions. Aprojecting actuator arm or fastening member may be useful with respectto the spinal screw implantation process or the rod reduction process,but there is insufficient clearance to use such structure and/or suchstructure may produce additional invasive trauma which the percutaneoussurgery is attempting to avoid.

A percutaneous procedure also presents a problem with implantation ofrods that are elongate and have historically required a long incisionand open wound in order to provide for the length of the rod and thespace required for the surgeon's hands to manipulate the rod. Suchproblems are then compounded by the implants and insertion tools usedwith the rod.

Consequently, it is desirable to develop apparatuses and techniques thatallow for the insertion of bone screws, the insertion and reduction of arod into the bone screws and the securing of the rod to the bone screwswith significantly less invasion into the body of the patient and withminimal surgical incision of the skin over the operational site.

SUMMARY OF THE INVENTION

A tool assembly and a set of tools according to the invention isprovided for percutaneously implanting bone screws and an associatedspinal rod in a patient. The tool assembly includes an elongate guidetool with implant engaging members and a multi-purpose installationtool. The multi-purpose tool is a stabilizer for the guide tool implantengaging members which also functions as a rod stabilizer tang containerand deployer and a rod pusher and reducer. The guide tool has a lowerend configured with opposed implant engaging members for releaseableattachment to a spinal implant bone screw, hook, etc. The multi-purposeinstallation tool is elongate, and preferably includes a translation nutand attached sleeve which has a lower end for engaging and containingthe rod stabilizer tang prior to rod insertion and later pushing on therod for reduction. The translation nut is coaxial and freely rotatablewith respect to the sleeve. The nut is configured for rotatableattachment to an upper end of the guide tool. The multi-purposeinstallation tool sleeve is attachable or securable to the guide tool ina first bone screw implantation orientation and in an alternative secondrod pushing orientation. In the first, bone screw implantationorientation, the sleeve is disposed in a fixed, stationary position withrespect to the guide tool, with the sleeve substantially surrounding theguide tool and retaining a flexible tang. In the second or rod pushingorientation, the sleeve is slidable along an axis of the guide tool andthe nut can be rotated, thereby translating the rod pushing end betweena first location substantially spaced from the guide tool end and asecond location near the guide tool end for rod reduction.

The tool assembly may further include a driver having a handle, a guidetool attachment portion and a stem, the stem having an end configuredfor rotatable engagement with a spinal implant screw. The driver is incoaxial relationship with both the guide tool and the multi-purposeinstallation tool when the stem is disposed within the guide tool withthe guide tool attached to the multi-purpose installation tool. Theattachment portion of the driver is configured for rigid attachment tothe guide tool, preventing rotation of the driver in relation to theguide tool.

A tool set according to the invention includes at least a pair of endguide tools. Each end guide tool includes an elongate body havingopposed implant engaging members with lower attachment structure adaptedfor attachment to a respective bone screw. The body has an inner surfacedefining an elongate and laterally opening channel. Preferably, theguide tool body further defines an elongate opening communicating withthe channel and a back wall with a flexible holding structure, the walland holding structure disposed opposite the lateral opening. The backwall flexible holding structure includes first and second elongate andparallel slits in the lower back wall portion creating a movable tab ortang disposed between the first and second slits. The flexible flap ortang partially defines the elongate channel. Furthermore, duringinsertion procedures, the tang may be pushed so as to flex, hinge orspring at an upper end thereof and so that a lower end angulates andtranslates outwardly or to a location lateral relative to a remainder ofthe back wall, with the channel adapted to receive a respective rodtherein. When an end of the rod is inserted in the lower end channel,the tang may be resiliently flexed further outwardly to accommodate thelength of the rod while maintaining, containing and stabilizing the rodin a desired position relative to bone screws.

The multi-purpose installation tool is attachable to the end guide toolin a first, bone screw implantation configuration position and in anopposite second, rod pushing configuration or position. In the firstposition, an elongate slot or opening in the sleeve of the tool supportis aligned with and fixed in adjacent relationship to the channelopening of the end guide tool, with the sleeve of the tool being heldadjacent to the back wall portion and retaining the spring tang. In thesecond, rod pushing position, the end guide tool back wall portion andthe tool sleeve opening are fixed in adjacent relationship with the backwall tang portion protrudeable into the tool sleeve opening.

An intermediate guide tool according to the invention includes an endwith opposed first and second implant engaging legs defining alongitudinal pass-through opening, passageway or slot for receiving arod therethrough. When attached to a multi-purpose installation tool inthe first, bone screw implantation orientation, the tool sleeve isdisposed in a fixed, stationary position substantially surrounding andsupporting both the intermediate guide tool legs. In the second or rodpushing orientation, the sleeve is in sliding relation along an axis ofthe intermediate guide tool, with the sleeve and associated rod pushingend translatable along the first and second legs between a firstlocation spaced from the intermediate guide tool end and a secondlocation adjacent or near the guide tool end.

A vertebral support rod implantation kit according to the invention,adapted for use with a plurality of vertebrae, includes a plurality ofpolyaxial bone screws, each bone screw being adapted for implantation inone vertebra, each of the bone screws having an attachment structure.The kit also includes an elongate rod having first and second ends, therod sized and shaped to extend between a pair of end bone screws of theplurality of bone screws. The kit further includes a plurality ofclosure tops with each closure top being sized and shaped to mate with arespective bone screw and capture or retain the elongate rod within acavity or channel defined by the respective arms of the bone screw.Additionally, the kit includes a pair of end guide tools, and mayinclude one or more intermediate guide tools, each guide tool beingattachable to multi-purpose installation tools, as described herein andbone screw drivers, the drivers being configured to be rigidly attachedto a respective end guide tool or intermediate guide tool.

In a method according to the invention, a spinal fixation tool assemblyis assembled by first attaching a bone screw head of a spinal implantscrew to a mating attachment structure disposed at a first end of anelongate guide tool implant engaging member, the guide tool defining alaterally opening channel and having a second attachment structuredisposed at a second end thereof. The guide tool and attached spinalimplant screw are then inserted into a multi-purpose installation tool,the tool having a translation nut and a sleeve. The nut is rotated in afirst direction to mate the tool support with the second attachmentstructure on the guide tool and translate the sleeve to a location nearthe guide tool first end. Then, a driver is inserted into the guide toolchannel, the driver having a handle and a spinal implant screwengagement end. The driver is attached to the guide tool at the secondattachment structure with the driver engagement end engaging the spinalimplant screw.

A method according to the invention may also include the steps ofinserting the attached driver, multi-purpose installation tool, guidetool and spinal implant screw into an incision, especially a minimallyinvasive incision sized to snugly or closely receive the assembled toolsand bone screw, and into contact with a vertebra, followed by turningthe driver handle. By turning the handle, the driver, the associatedtools and the spinal implant screw are rotated as one assemblage orunit, driving the spinal implant screw into the vertebra.

Further method steps according to the invention include detaching thedrivers from the attached guide and multi-purpose installation tools andwithdrawing the drivers from the incisions, followed by detaching themulti-purpose installation tools from the end guide tools and therebydeploying the end tangs. It may also be desirable to detach themulti-purpose installation tools from the intermediate guide tools, ifany.

According to the invention, during rod insertion, a respectivemulti-purpose installation tool may be utilized for rod reduction andaccordingly replaced on each end guide tool with the sleeve openingthereof aligned with the end guide tool flexible wall or tang to allowthe tang to remain flexed outward. Then a rod first end may be insertedinto an incision through which one of the end guide tools has beeninserted, and then guided into a channel of an adjacent end orintermediate guide tool. The rod is then guided into and through allremaining channels with first and second ends of the rod each in contactwith a flexible wall or deployed tang of a respective end guide toolwith the tangs biasing against the rod ends, and with the rod extendingthrough all associated guide tools. The multi-purpose installation toolsleeve is then utilized as a rod pusher by rotating the nut and slidingthe closed end of the sleeve toward the lower guide tool end, the sleeveend contacting the rod and pushing the rod toward the bone screw.

The attachment structure for joining the guide tool to the bone screwincludes radial mating projections and receivers or grooves that allowthe guide tool to be twisted on and twisted from the head of the bonescrew. For example, an external attachment on the bone screw head canhave tapered undercut upper surfaces. It is foreseen that otherattachment structure could be used such as clip-on/clip-off,clip-on/twist-off, snap-on/snap-off, snap-on/twist-off,spring-on/spring-off, spring-on/twist-off, set screws, etc. Theattachment structure secures the guide tool to the bone screw duringinsertion of the screw into bone, but allows the tool to release fromthe bone screw for removal of the tool at the end of the procedure byrotation of the tool about a central axis thereof or by some othermechanism, as described herein.

Objects and Advantages of the Invention

Therefore, the objects of the present invention are: to provide acompact tool assembly for supporting and installing bone screws andother implants with minimal surgical invasion to the patient; to providesuch an assembly wherein a tool providing support and stabilization forimplant engaging members of the assembly during bone screw implantationmay also be utilized for deployment of rod containment tangs and as arod reducer; to further provide a set of tools for implanting a spinalrod for support or alignment along a human spine with minimal surgicalinvasion of the patient; to provide such a set of tools including a pairof end tool guides for slidably guiding opposed ends of the rod towardend bone screws attached to the end guide tools; to provide such a setof tools including intermediate guide tools for each intermediate bonescrew that guide the rod in slots therethrough to respective bonescrews; to provide such a set of tools including rod and closure topinstallation tools for assisting in securing the rod in the bone screws;to provide such a set of tools wherein the guide tools are easilyattached to and disengaged from the bone screws; to provide such a setof tools wherein the guide tools, guide tool supports or stabilizers,tang containment and deployment tools, rod reduction tools, bone screwinstallation tools and closure top installation tools are all easilyaligned, positioned, and engaged, if necessary, with respect to the bonescrew and are disengaged from the bone screw and other tools in theinstallation assembly by manual manipulation of the surgeon; to providea method of implanting a rod into bone screws within a patient withminimal surgical invasion of the patient; to provide such a methodutilizing the previously described tools for percutaneous implantationof such a rod; and to provide such a set of tools and methods that areeasy to use and especially adapted for the intended use thereof andwherein the tools are comparatively inexpensive to produce.

Other objects and advantages of this invention will become apparent fromthe following description taken in conjunction with the accompanyingdrawings wherein are set forth, by way of illustration and example,certain embodiments of this invention.

The drawings constitute a part of this specification and includeexemplary embodiments of the present invention and illustrate variousobjects and features thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded front elevational view of a tool assemblyaccording to the present invention showing a driver tool, amulti-purpose installation tool implant engaging member stabilizersleeve/tang container and deployer/rod pusher and reducer and an endguide tool shown with an attached polyaxial bone screw.

FIG. 2 is an enlarged front elevational view of an intermediate guidetool of the invention.

FIG. 3 is an enlarged side elevational view of the intermediate guidetool of FIG. 2 .

FIG. 4 is an enlarged rear elevational view of the intermediate guidetool of FIG. 2 .

FIG. 5 is an enlarged front elevational view of the end guide tool ofFIG. 1 .

FIG. 6 is an enlarged side elevational view of the end guide tool ofFIG. 5 .

FIG. 7 is an enlarged rear elevational view of the end guide tool ofFIG. 5 .

FIG. 8 is a cross-sectional view of the end guide tool, taken along theline 8-8 of FIG. 5 .

FIG. 9 is an enlarged cross-sectional view of the intermediate guidetool, taken along the line 9-9 of FIG. 2 .

FIG. 10 is an enlarged cross-sectional view of the intermediate guidetool, taken along the line 10-10 of FIG. 2 .

FIG. 11 is an enlarged bottom plan view of the intermediate guide toolof FIG. 2 .

FIG. 12 is an enlarged and fragmentary perspective view of a polyaxialbone screw of the invention.

FIG. 13 is an enlarged and fragmentary front elevational view of thepolyaxial bone screw of FIG. 12 .

FIG. 14 is an enlarged and fragmentary side elevational view of thepolyaxial bone screw of FIG. 12 .

FIG. 15 is an enlarged and fragmentary side elevational view of thepolyaxial bone screw of FIG. 12 disposed opposite the side shown in FIG.14 .

FIG. 16 is an enlarged top plan view of the polyaxial bone screw of FIG.12 .

FIG. 17 is an enlarged and fragmentary front elevational view of thepolyaxial bone screw of FIG. 12 and the intermediate guide tool of FIG.2 , shown at an early stage of a twist-on installation of theintermediate guide tool to the bone screw head.

FIG. 18 is an enlarged and fragmentary cross-sectional view of theintermediate guide tool and polyaxial bone screw installation, takenalong the line 18-18 of FIG. 17 .

FIG. 19 is an enlarged and fragmentary cross-sectional view similar toFIG. 18 , showing a later stage of the twist-on installation of theintermediate guide tool to the bone screw head.

FIG. 20 is an enlarged and fragmentary cross-sectional view similar toFIGS. 18 and 19 , showing the intermediate guide tool installed on thebone screw head.

FIG. 21 is an enlarged, fragmentary and cross-sectional view, takenalong the line 21-21 of FIG. 20 , showing the intermediate guide toolinstalled on the bone screw head.

FIG. 22 is an enlarged front elevational view of the multi-purpose toolshown in FIG. 1 .

FIG. 23 is a cross-sectional view of the multi-purpose tool taken alongthe line 23-23 of FIG. 22 .

FIG. 24 is an enlarged bottom plan view of the multi-purpose tool ofFIG. 22 .

FIG. 25 is an enlarged and fragmentary cross-sectional view of a portionof the multi-purpose tool shown in FIG. 23 .

FIG. 26 is an enlarged and fragmentary side elevational view of thedriver shown in FIG. 1 having a handle, a nut fastener and a stem, withthe nut fastener being shown in a first, unengaged position.

FIG. 27 is an enlarged and fragmentary front elevational view of thedriver tool similar to FIG. 26 , showing the nut fastener in a second orintermediate position.

FIG. 28 is an enlarged and fragmentary side elevational view similar toFIG. 27 and further showing a cross-sectional view of the nut fastener,taken along the line 28-28 of FIG. 27 .

FIG. 29 is an enlarged cross-sectional view similar to FIG. 23 , showingan early stage of the installation of the multi-purpose tool to the endguide tool (shown in side elevation as in FIG. 6 ).

FIG. 30 is an enlarged cross-sectional view similar to FIG. 29 , showingthe multi-purpose tool installed to the end guide tool (shown in sideelevation).

FIG. 31 is an enlarged cross-sectional view of the multi-purpose tool,taken along the line 31-31 of FIG. 30 , showing the end guide tool infront elevation.

FIG. 32 is an enlarged and fragmentary cross-sectional view of themulti-purpose tool similar to FIG. 31 , shown attached to the end guidetool and also showing a sliding engagement stage of attachment to thedriver (shown in front elevation).

FIG. 33 is an enlarged and fragmentary front elevational view similar toFIG. 32 , showing the driver nut fastener in the intermediate positionshown in FIG. 27 .

FIG. 34 is an enlarged and fragmentary front elevational view similar toFIG. 33 , showing the driver in fixed engagement with the guide tool.

FIG. 35 is an enlarged and fragmentary view similar to FIG. 34 , showingthe driver in fixed engagement with the guide tool and with the drivernut fastener shown in cross-section as in FIG. 28 , and themulti-purpose tool shown in cross-section as in FIG. 32 .

FIG. 36 is a partial and generally schematic cross-sectional view of apatient's spine, showing a thin guide pin installed at a first sidethereof and a bone screw tap tool and threaded bore made thereby at asecond side thereof.

FIG. 37 is a partial and generally schematic view of a patient's spineshowing a tool assembly according to the invention with attached bonescrew being guided toward the threaded bore in a vertebra in an earlystage of a process according to the invention.

FIG. 38 is a partial and generally schematic view of a patient's spine,showing an end guide tool and the multi-purpose tool of the presentinvention being positioned for use in a process according to theinvention.

FIG. 39 is a partial and generally schematic view of a patient's spine,showing a pair of end tools and a pair of intermediate tools of thepresent invention being positioned for use in a process according to theinvention.

FIG. 40 is a partial and generally schematic view of a patient's spine,showing a pair of end tools with the flexible tangs containing a rodwhich has now been inserted and a pair of intermediate tools of thepresent invention with one of the intermediate tools shown with anattached multi-purpose tool in a rod reduction application and one ofthe end guide tools shown partially cut-away, illustrating a closure topinstallation tool disposed within the end tool and cooperating with abone screw closure member, the tools being utilized in an early stage ofrod implantation to guide the rod toward the bone screws.

FIG. 41 is a partial and generally schematic cross-sectional view of thespine, taken along the line 41-41 of FIG. 40 , showing an early stage ofimplanting a rod according to a process of the invention.

FIG. 42 is a partial and generally schematic view of a patient's spinesimilar to FIG. 40 , showing cut-away portions of all four toolassemblies, illustrating an intermediate stage of implanting a rod.

FIG. 43 is a partial and generally schematic view of a patient's spinesimilar to FIG. 42 , showing cut-away portions of three of the toolassemblies and one assembly without an end tool, illustrating the rodfully installed in all the bone screws.

FIG. 44 is an exploded front elevational view of an anti-torque toolassembly according to the present invention showing an antitorque tooland a closure top installation tool cooperating with a break-away bonescrew closure member.

FIG. 45 is a bottom plan view of the anti-torque tool shown in FIG. 44 .

FIG. 46 is a fragmentary and front elevational view of a bone screw withattached break-away closure member and installed rod, and furthershowing the closure top installation tool of FIG. 44 with theanti-torque tool.

FIG. 47 is a fragmentary and front elevational view of a bone screw andanti-torque tool with portions broken away to show a torque driveradvancing toward the break-away closure member in a process according tothe invention.

FIG. 48 is a fragmentary and front elevational view of the bone screwand anti-torque tool similar to FIG. 47 , with portions broken away toshow a fully installed rod and closure member with the break-away headremoved from the top by the torque driver.

FIG. 49 is an enlarged fragmentary side elevational view of the bonescrew head with the closure installed therein, the closure and bonescrew head incorporating the interlocking form according to the presentinvention with portions broken away to show detail thereof.

FIG. 50 is a view similar to FIG. 49 and illustrates details of firstmodified bone screw and closure showing a medial bead embodiment of aninterlocking form of the present invention.

FIG. 51 is view similar to FIG. 49 and illustrates details of a secondmodified bone screw and closure showing an axial aligned shoulderembodiment of an interlocking form of the present invention,

FIG. 52 is a view similar to FIG. 49 and illustrates details of a thirdmodified bone screw and closure showing an axial bead embodiment of aninterlocking form of the present invention.

FIG. 53 is a view similar to FIG. 49 and illustrates details of a fourthmodified bone screw and closure showing a shallow axial bead embodimentof an interlocking form of the present invention.

FIG. 54 is a view similar to FIG. 49 and illustrates details of a fifthmodified bone screw and closure showing a radial bead embodiment of aninterlocking form of the present invention.

FIG. 55 is a view similar to FIG. 49 and illustrates details of a sixthmodified bone screw and closure showing a scalloped depression orscooped embodiment of an interlocking form of the present invention.

FIG. 56 is a fragmentary cross sectional view of a seventh modified bonescrew and closure, similar to the embodiment in FIG. 55 , showing a pairof interlocking forms in accordance with the present invention.

FIG. 57 is a fragmentary cross sectional view of an eighth modifiedembodiment of a bone screw and closure showing a pair of interlockingforms in accordance with the invention.

FIG. 58 is a fragmentary cross sectional view of an ninth modifiedembodiment of a bone screw and closure showing a pair of interlockingforms in accordance with the invention.

FIG. 59 is a fragmentary cross sectional view of an tenth modifiedembodiment of a bone screw and closure showing a pair of interlockingforms in accordance with the invention.

FIG. 60 is a perspective view of an example closure for an open headedbone screw that has a helical wound gripping interlocking form inaccordance with the present invention mounted thereon.

FIG. 61 is a side elevational view of the closure.

FIG. 62 is a side elevational view illustrating an interlocking form ofthe closure mated with and installed in a companion interlocking form onan open headed bone screw to capture a fixation rod within a head of thebone screw and with the head of the bone screw partially broken away toillustrate detail thereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure.

With reference to FIG. 1 , and for example, also FIGS. 37 and 40 ,reference numeral 1 generally designates a tool assembly according tothe present invention and reference numeral 2 generally designates atool set according to the invention, made up of a number and variety oftool assemblies 1 for use in installing a set of bone screws 4 into apatient's spine 6, followed by the installation of an orthopedic spinalrod or longitudinal member 8 into the bone screws 4 in a processaccording to the present invention.

The tool assembly 1 includes an end guide tool 9 or an intermediateguide tool 10 mated with a multi-purpose installation tool 12 configuredto function as a guide tool stabilizer and supporter, a tang containerand deployer and a rod pusher and reducer. The tool assembly 1 mayfurther include a driver 14. A set 2 of the illustrated embodimentincludes a pair of end guide tools 9 and a plurality of intermediateguide tools 10, which in the illustrated embodiment includes a pair ofintermediate guide tools 10 on each side of a patient's spine 6, butwhich can include none, one or many intermediate guide tools 10depending upon the particular application, so that one intermediateguide tool 10 is used for each intermediate bone screw 4 to which therod 8 is to be attached.

The driver 14 is used in conjunction with the guide tool 9 and the guidetool 10 to implant bone screws 4 in the patient's spine 6 and, inparticular, in vertebrae 16 along the spine 6 as shown in FIG. 37 . Eachend guide tool 9 and intermediate guide tool 10 is configured tocooperate with the multi-purpose installation tool 12 to install the rod8. However, it may be sufficient according to a process of the inventionto utilize only one multi-purpose installation tool 12 in a particulartool set 2, as shown in FIG. 40 . Rods 8 or other longitudinal membersare often installed on both sides of the spine 6 during the sameprocedure.

It is noted that any reference to the words top, bottom, up and down,and the like, in this application refers to the alignment shown in thevarious drawing figures, as well as the normal connotations applied tosuch devices, and is not intended to restrict positioning of theassembly 1 or the tool set 2 in actual use.

The end guide tool 9 is illustrated in FIG. 1 and FIGS. 5 through 8 . Inparticular, each end guide tool 9 has an elongate body 18 that is sizedand shaped to be sufficiently long to extend from implanted bone screws4 through an exterior of a patient's skin 20 so as to provide anoutwardly extending and upper handle portion 22 that allows and providesfor gripping by a surgeon during procedures utilizing the tool set 2,with or without an attached multi-purpose installation tool 12 and/ordriver 14.

Each of the end guide tools 9 further includes an intermediate portion24 and a lower implant engaging portion 26 which includes opposedimplant engaging members for securing one the implants there between.Each end guide tool 9 has a substantially flat back wall 28 joining apair of substantially cylindrically shaped side walls 32 and 33. Theback wall 28 provides a flexible holding structure that includes a pairof parallel slits 34 extending from near the lower handle portion 22 toan end 36 of the tool 9. When pressed upon by a rod 8, a flap orflexible tang 38 disposed between the slits 34 in the back wall portionis configured to flex or spring radially outwardly from the bottom andabout the top thereof in a deployed position, as is shown in FIG. 6 .The back wall portion flap or tang 38 provides a surgeon with someadditional working space and flexibility when working with the rod 8during surgery, so the rod 8 can extend beyond the bone screws 4 whileremaining under resilient tension produced by outward biasing of theflexible back wall portion so that the rod 8 remains in a desiredposition and under control. Further, the tang or flap 38 also functionsto urge the rod 8 toward the other tools in the tool set 2, as shown inFIG. 40 and as will be discussed more fully below.

The upper portion 22 of each end guide tool 9 includes a laterally orsideways opening channel 39, forming a U-shaped cross-section, aC-shaped cross-section, a crescent shaped cross-section or the likehaving a generally elongate and axially extending opening 40 with aside-to-side width 42. Preferably, the channel 39 mates with otherchannel structure described below so as to extend the entire length ofthe end guide tool 9. The opening 40 communicates with and forms part ofthe channel 39 that opens at an upper end 43 of the guide tool 9 andalso opens perpendicularly with respect to a central axis of the guidetool 9 or laterally to one side of the end guide tool 9, thus definingthe opening 40. The opening 40 narrows near the upper end 43 providing aslot 44 having a side-to-side width 45 that is smaller than theside-to-side width 42. The slot 44 is configured for sliding engagementwith a rotational locking pin 46 disposed on the driver 14 and discussedmore fully below. Disposed on either side of the slot 44 are co-planarsurfaces 47 and 48 that are parallel with the back wall 28. The surfaces47 and 48, as well as the back wall 28, provide alignment surfaces whenthe multi-purpose tool 12 is inserted onto the guide tool 9 discussedmore fully below.

The opening 40 is of substantially constant width through a mid-section48 of the handle portion 22, sufficiently wide to receive additionaltools and/or a closure top for sideways loading into the channel 39, aswill be discussed below.

The upper portion 22 also includes an outer helically wounddiscontinuous guide and advancement structure 50 disposed on outersurfaces of both of the substantially cylindrically shaped side walls 32and 33, which may include conventional helically wound V type threads,buttress threads, helically wound square threads, or other guide andadvancement structure to cooperate with equivalent or mateable structurewithin the multi-purpose installation tool 12 and the driver 14, asdescribed more fully below. The advancement structure 50 extends fromnear the intermediate portion 24 to the open end 43. The back wall 28extending between the threaded sides 32 and 33 has an outersubstantially planar and smooth surface finish.

Extending from the upper portion 22 and into the intermediate portion 24of each end guide tool 9 is an outward facing channel 51 that has anopening 52 with a side-to-side width 53 that is somewhat smaller thanthe width 42 of the upper handle portion 22, such that the channel 51and opening 52 are sized and shaped to receive and allow passage ofcertain tools and implants, as described below.

Furthermore, a remaining portion of the end guide tool intermediateportion 24 and the lower portion 26 includes a groove or channel 55,with an elongate, axially extending and radially outward opening 57,having a side-to-side width 58 that is slightly smaller than the width42 of the opening 40, but larger than the slot width 45 and the openingwidth 53. The channel opening 57 is disposed opposite the flexible tangor flap 38. All of the channels 39, 51 and 55 communicate with oneanother and are aligned with one another so as to provide a continuouselongate interior and sideways open passageway with an open side fromnear the top end 43 to near the bottom 36 thereof. This passagewayprovides a continuous open path of non-uniform cross-sectional radiusthroughout from the top 43 to the bottom 36 thereof that is parallel toan elongate axis A of each end guide tool 9. As will be discussed morefully below, each end guide tool channel opening 57 is sized and shapedto slidingly receive a respective end 59 of the rod 8 therein. It isforeseen that one or all of the channel openings forming the open sidethat extends from near the top end 43 to near the bottom 36 of the guidetool 9 may be sized and shaped to receive the end 59 of the rod 8. It isalso foreseen that the rod 8 may be of uniform or non-uniform diameter,regular or uneven surface construction, or smooth or roughened surfacefinish, and that the channel openings may in turn be sized and shaped toreceive such a rod end that may exhibit a greater or smaller width ordiameter than at other locations along the rod.

The slits 34 are spaced in order to have a back wall or flap flex regionhaving a size and shape to allow at least partial passage of arespective end 59 of the rod 8 between the side walls 32 and 33. Alsolocated near the end guide bottom 36 is a rod abutment recess 61 that issized and shaped for the purpose of bridging the rod 8 when the endguide tool 9 is rotated for removal, as described below. However, it isforeseen that other removal means could be used. The end guide tool 9also receives a closure top 62, as will be described below. Stillfurther, near the bottom 36 of each of the end guides 9 on innersurfaces of the side walls 32 and 33, is a helical wound, discontinuousguide and advancement structure 64 which may include conventionalhelically wound V-shaped threads, buttress threads, reverse anglethreads, helically wound square threads, or other guide and advancementstructure to cooperate with equivalent or mateable structure within thebone screw heads 4 and on the closure top 62, as also described below.

At the lower portion 26, the substantially cylindrical side walls 32 and33 include an outer radially extending bevel 66 and substantiallycylindrical outer side walls 68 and 69, respectively. The walls 68 and69 uniformly increase the thickness of the respective side walls 32 and33, resulting in a substantially cylindrical cross-section of greaterdiameter than a diameter created by an outer surface of the side walls32 and 33 at the intermediate portion 24.

As will be discussed more fully below, in addition to increasing thediameter, the walls 68 and 69 are configured with co-planar front wallsor facets 70 and co-planar back walls or facets 71 with the facets 70being disposed parallel to the facets 71, providing for alignment andmating with an interior of the multi-purpose installation tool 12 toensure that the end guide tool 9 is retained in a selected,non-rotatable position with respect to the multi-purpose installationtool 12 when installed therein. Each of the walls 68 and 69 can includean abutment pin 67 located at an outer surface thereof and near thebottom or end 36. The pin 67 may serve as a stop for the multi-purposeinstallation tool 12 as will be described more fully below; however,such a pin stop is not always needed.

Near the end or bottom 36 of each end guide tool 9, disposed on an innersurface of each of the side walls 32 and 33, is a radially inward facingattachment structure, generally 72, that will be described below inconjunction with a similar structure on the intermediate guide tool 10and the bone screw 4.

Each of the intermediate guide tools 10, specifically illustrated inFIGS. 2 to 4 , have a somewhat similar overall shape when compared tothe end guide tools 9 in that both are preferably of the same axiallength and width and also have much structure in common; however withcertain differences as noted. Each intermediate guide tool 10 has anoverall elongate body 74 with an upper handle portion 76, anintermediate portion 77 and a lower implant engaging portion 78 whichincludes opposed implant engaging members for securing one of theimplants there between. In the upper portion 76, the body 74 isgenerally C-shaped defining a radially outward opening 79 communicatingwith an elongate and axially extending channel 80 defined by a rear wall81 having a lower web edge 96 and side walls 82 and 83. With referenceto FIG. 2 , the channel 80 front opening 79 extends parallel to an axisB of the body 74 and has a side-to-side width 85 configured to receivetools and elements described below.

Similar to the end guide tool 9, the opening 85 narrows near an upperend 87 providing an elongate slot 88 having a side-to-side width 89 thatis smaller than the width 85. The slot 88 is configured for slidingengagement with the pin 46 disposed on the driver 14 and discussed morefully below. Disposed on either side of the slot 88 are co-planarsurfaces 91 and 92 that are parallel with the rear wall 81. The surfaces91 and 92, as well as the rear wall 81, provide alignment surfaces whenthe multi-purpose tool 12 is inserted onto the guide tool 10, discussedmore fully below. Below the slot 88, the side-to-side opening width 85is substantially constant through a mid-section 90 of the handle portion76, sufficient to receive additional tools and/or a closure top, as willbe discussed below.

The upper or handle portion 76 also includes an outer helically wounddiscontinuous guide and advancement structure 93 disposed on outer sidesof both of the substantially cylindrically shaped side walls 82 and 83,which may include conventional helically wound V-threads, helicallywound square threads, buttress threads or other guide and advancementstructure to cooperate with equivalent or mateable structure within themulti-purpose installation tool 12 and the driver 14 as described morefully below. The advancement structure 93 extends from near theintermediate portion 77 to the open end 87. An outer surface of the rearwall 81 extending between the threaded sides 32 and 33 is substantiallyplanar and smooth.

The upper or handle portion 76 further includes an outward facingchannel 94 communicating with the channel 80. The channel 94 is definedin part by a rear wall or web 95 having a lower end with the web edge96, the wall 95 being integral with the wall 81. Communicating with thechannel 94 is an elongate and axially extending opening 98 having aside-to-side width 99 that is somewhat smaller than the width 85 of theopening 79. The opening 98 is further defined by the walls 82 and 83.The channel 94 and opening 98 are configured to receive, contain andallow translational movement therealong or rotational relative movementof certain tools, as described more fully below. Although not shown inthe drawings, it is foreseen that the channel 94, channel opening 98 andrear wall or web 95 may extend into the intermediate portion 77 toprovide greater strength and stability to the lower portion 78 of theintermediate tool 10, with the opening 98 also extending into the lowerportion 78 providing greater retention of small tools or parts beinginserted through the channel 94.

The intermediate portion 77 of the intermediate tool 10 includes twospaced side walls or legs 102 and 103, extending from and integral withthe side walls 82 and 83, respectively. The legs 102 and 103 have outersurfaces that are partially cylindrical.

Similar to the end tool 9, at the juncture of the intermediate portion77 and the lower portion 78, each of the legs 102 and 103 include anoutwardly facing radially extending bevel 106 integral withsubstantially cylindrical outer side walls 107 and 108, respectively.The outer walls 107 and 108 extend along the length of the lower portion78 and uniformly increase the thickness of the respective legs 102 and103, resulting in a substantially cylindrical cross-section of greaterouter diameter at the lower portion 78 than an outer diameter created bythe outer surfaces of the legs 102 and 103 along the intermediateportion 77. As will be discussed more fully below, in addition toincreasing the diameter, the walls 107 and 108 are configured withco-planar front facets or walls with flat surfaces 109 and co-planarrear facets or walls with flat surfaces 110, the facets 109 disposedparallel to the facets 110, providing for alignment with an interior ofthe multi-purpose installation tool 12 to ensure that the intermediateguide tool 10 is properly mated with and retained in a selected,non-rotatable position with respect to the multi-purpose installationtool 12 when installed therein.

Along both the intermediate and lower portions 77 and 78 of theintermediate tool 10, the legs 102 and 103 define an elongate andaxially extending passthrough slot 111 sized and shaped to slidinglyreceive the rod 8. The slot or opening extends from the lower edge ofthe web end 96 of the rear wall 95 to an open end or bottom 112 of thetool 10 configured to secure an open ended spinal surgery implant therebetween.

Near the bottom 112 of each implant engaging leg member 102 and 103 ofthe intermediate guide tool 10 is a helically wound but discontinuoussquare thread 114 and it is foreseen that other type of guide andadvancement structure may be utilized such as helically wound flangeforms, reverse angle threads, buttress threads, etc. The thread form 114cooperates with the closure top 62, as described below. The lower end ofeach leg 102 and 103 of the intermediate guide tool 10 also includes acutout or rod-abutment recess 116 similar to the recess 61 describedwith respect to the end tool 9. Each of the walls 107 and 108 caninclude an abutment pin 118 located at an outer surface thereof and nearthe bottom or end 112. The pin 118 may serve as a stop for themulti-purpose installation tool 12 as will be described more fullybelow.

Also near the end or bottom 112 of each leg 102 and 103 of theintermediate guide tool 10, disposed on inner substantially cylindricalsurfaces 120 and 121, respectively, is a radially inward facingattachment structure, generally 124, substantially similar to thestructure 72 disposed on the end guide tool 9. The structure 124 will bedescribed herein in conjunction with the bone screw 4.

With reference to FIGS. 9-11 , the embodiment shown includes anattachment structure 124 having a first projection, stop or pin 126 inspaced relation with a second smaller projection, stop or pin 127, bothpins being disposed on the surface 120. In the embodiment shown, thestructure 123 further includes a cooperating third projection, stop orpin 130 in spaced relation with a fourth smaller projection, stop or pin131, the pins 130 and 131 being disposed on the surface 121.

The larger pins 126 and 130 are substantially configured the same, bothbeing substantially rounded, radially inward projecting nodules, eachhaving a ridge or lip 132 and 133, respectively, projecting upwardlytoward the guide and advancement structure 114 and that preferablyfollows the curvature of the respective leg inner surface 120 and 121.

The lips 132 and 133 with respective surfaces 120 and 121 define slots134 and 135, respectively, for receiving the bone screw 4 as will bediscussed more fully below. The pin 126 is configured slightly largerthan the pin 130, requiring similar modification in the bone screw 4,resulting in a method of operation wherein the bone screw 4 may only bemated with the guide 9 or 10 from a single direction, ensuringappropriate alignment between the bone screw 4 and guide tooladvancement structure 114 with respect to the installment of the closuretop 62.

Each of the larger pins 126 and 130 is also disposed at substantiallythe same distance from respective bottom surfaces 138 and 139, at theend 112 of the guide tool 10 and adjacent a rod-abutment recess 116.Furthermore, each of the larger pins 126 and 130 is also disposed atsubstantially the same distance from respective parallel seatingsurfaces 140 and 141, that form a base of the guide and advancementstructure 114. Additionally, in this embodiment the pins 126 and 130 aredisposed in diametrically opposed relation when viewed in cross-sectionas shown in FIG. 10 .

The smaller pins 127 and 131 are also substantially configured the same,the pin 131 being slightly larger than the pin 127, but otherwise bothpins 127 and 131 being substantially rounded, radially inwardlyprojecting nubs, each disposed at substantially the same distance fromthe respective bottom surfaces 138 and 139 and the respective seatingsurfaces 140 and 141. Furthermore, the pins 127 and 131 are disposed indiametrically opposed relation when viewed in cross-section as shown inFIG. 10 . Each of the pins 127 and 131 are disposed closer to therespective end surfaces 138 and 139 than are the larger pins 126 and130. It is noted that other orientations and pin sizes may be utilizedaccording to the invention, with the pin sizes and locations cooperatingwith respective features on the bone screws 4. Preferably, the pins areof different sizes to provide for mating of the guide tool 9 or 10 withthe bone screw 4 from a single direction, resulting in a desiredalignment between the bone screw 4 guide and advancement structure 114and the closure top 62 guide and advancement structure.

The pins 126, 127, 130 and 131 cooperate and mate with the bone screw 4,at a receiver portion, generally identified by the reference numeral145, of a head 146 thereof. With reference to FIGS. 12-15 , each of thebone screws 4 further includes a threaded shank 148 attached to the head146, the shank 148 for screwing into and seating in a vertebra 16 thatis part of the human spine 6. The head 146 includes first and secondarms 150 and 151 that define a rod receiving channel 153 passingtherethrough. Each of the bone screw shanks 148 includes an upperportion 154 that extends into the head 146 and is operationally securedtherein, so that the head 146 is rotatable on the shank 148 until lockedin position through engagement with the rod 8 under pressure.

The receiver portion 145 is disposed on outer surfaces of the arms 150and 151. The receiver portion 145 of arm 150 includes a slot or groove158 communicating with a recess 159 defined in part by a flange 160. Thegroove 158 and recess 159 open at a front surface 162 of the arm 150 andextend across a facet 163 and into a side surface 164 thereof. Withreference to FIG. 21 , the groove 158 is configured to mate with thelarge pin 126 with the lip 132 extending into the recess 159 and theflange 160 disposed in the slot 134 when the guide tool 10 is attachedto the bone screw head 146. The width of the slot 134 is sized toprevent passage therethrough of the pin 126 except by twisting orrotational relative movement therebetween. The receiver portion 145 ofthe arm 150 further includes a rounded aperture 165 disposedsubstantially centrally on a face or facet 167 of the arm 150, the facet167 disposed adjacent to the side surface 163. The aperture 165 isconfigured to mate with the small pin 127.

Similar to the arm 150, the receiver portion 145 of the arm 151 definesa groove 168 communicating with a recess 169 defined in part by a flange170. The groove 168 and recess 169 open at a back surface 172 of the arm151 and extend across a facet 173 into a side surface 174 thereof.

Similar to what is shown in FIG. 21 with respect to the arm 150, thegroove 168 is configured to mate with the large pin 130 with the lip 133extending into the recess 169 and the flange 170 disposed in the slot135 when the guide tool 10 is attached to the bone screw head 146. Thereceiver portion 145 of the arm 151 further includes a rounded aperture175 disposed substantially centrally on a face or facet 177 of the arm151, the facet 177 disposed adjacent to the side surface 173. Theaperture 175 is configured to mate with the small pin 131.

In the embodiment shown, to attach the bone screw head 146 to the guidetool 10, the guide tool 10 is rotated about its axis B such that thelegs 102 and 103 are lowered into place as shown in FIGS. 17 and 18 ,with the facets 167 and 177 of the head 146 disposed between the guidetool legs 102 and 103, with the facet 167 adjacent the leg 102 and thefacet 177 adjacent the leg 103, thereby aligning the groove 158 with thelarge pin 126 and the groove 168 with the large pin 130. The head 146may then be twisted into place as shown by the arrow T in FIGS. 18, 19and 20 . The legs 102 and 103 may splay slightly as the head is twistedinto place, but come to rest in a generally non-splayed configurationand held in place by the structure of the attachment mechanism to resistsplaying.

In order to disengage the guide tool 9 or the guide tool 10 from thebone screw 4, the guide tool 9, 10 is rotated counterclockwise from anattaching configuration (opposite to the arrow T), when viewing from thetop so as to disengage the lips 132 and 133 from the recesses 159 and169, respectively. In this manner, end guide tools 9 and intermediateguide tools 10 that have previously twisted on, now twist off ofrespective bone screws 4.

While a preferred embodiment of the invention has the respective pins ofthe attachment structure on the guide tools and the grooves on the bonescrew heads, it is foreseen that these elements could be reversed intotal or part in accordance with the invention. Also, other suitableattachment structure could be used, such as sloped or tapered undercutsurfaces on the screw heads that overlap, mate and interlock withradially or linearly projecting structure on or near the ends of theguide tools. Such projecting structure can be snapped on or clipped onand translated up to provide for anti-splay overlapping surfaces.

In the embodiment shown, the recesses 61 and 116 disposed on therespective guide tools 9 and 10 are sized, shaped and positioned so thatwhen the rod 8 is located in the bone screws 4, the guide tools 9 and 10can rotate about respective axes A and B, with the recess 61 and 116allowing the respective guide tool 9 and 10 to straddle over the rod 8,thereby allowing the guide tool 9 and 10 to twist relative to the bonescrew 4 and free the attachment structures 72 and 124 from the receiverportion 145 of the bone screw 4 and thereafter be removed after allprocedures are complete, as described below.

The closure top 62 closes between the spaced bone screw arms 150 and 151to secure the rod 8 in the channel 153. The closure top 62 can be any ofmany different plug type closures. With reference to FIGS. 46-48 ,preferably the closure top 62 has a cylindrical body 180 that has ahelically wound mating guide and advancement structure 181. The guideand advancement structure 181 can be of any type, including V-typethreads, buttress threads, reverse angle threads, or square threads.Preferably the guide and advancement structure 181 is a helically woundflange form that interlocks with a reciprocal flange form as part of aguide and advancement structure 183 on the interior of the bone screwarms 150 and 151.

A suitable locking guide and advancement structure of this type isdisclosed in U.S. Pat. No. 6,726,689 from Ser. No. 10/236,123 which isincorporated herein by reference. Referring to FIGS. 49 to 59 , thereference numeral 400 generally designates a gripping interlocking formarrangement incorporating a non-linear or compound surface whichembodies the present invention. The interlocking form arrangement 400includes an external interlocking form 402 and internal interlockingform 404 which have respective thrust surfaces 406 and 408 (FIG. 4 ) andwhich are used as pairs. The interlocking form arrangement 400 may beused on any of a number of interlocking formed devices, such as animplanted bone fixation system, including a receiver or open headedimplant member which receives a closure or closure member to secure afixation member therein. In the interlocking form arrangement 400, thethrust surfaces 406 and 408 are non-linear or compound in such a manneras to resist tendencies of arms 432, for example, to splay or expandwhen the closure member 410 is rotated therein.

The interlocking forms 402 and 404 are helical and are intended toadvance the closure member 410 linearly along the axis of rotation 412of the closure member 410 and the interlocking forms 402 and 404relative to another member as the closure member 410 is rotated relativeto a bone screw 4. A spatial reference for such rotation and linearmovement is along the axis 412 (FIG. 49 ). The axis 412 locates thecoincident axes of the external or radially outward interlocking form402 of a base 410 (e.g., a closure member 410) and the internal orradially inward interlocking form 404 of a head 414, when the base 410is inserted into the head 414 by starting at the top of the interlockingform 404 (top is up in FIG. 49 ) and rotated. The base 410 has a basiccylindrical shape, and the external interlocking form 402 includes aroot 416 and a crest 418 formed by cutting a helical wound channel ofthe desired cross section into the original surface of the base 410. Thecrest 418 of the external interlocking form 402 has a greater radiusthan the root 416. In a like manner, the internal interlocking form 404of the head 414 of a screw 4 has a helical channel under cut thereinto,forming a root 420 and crest 422. The root 420 of the internalinterlocking form 404 has a greater radius than the crest 422.

The thrust surfaces 406 and 408 respectively of the external andinternal interlocking forms 402 and 404 engage frictionally when thebase 410 is rotated into the head 414. The thrust surfaces 406 and 408are located on the trailing sides respectively of the crests 418 and422, as referenced to the tightening direction movement of the base 410into the head 414. In general, there is minimal contact between theclearance surfaces 424 and 426 when the base 410 is rotated in atightening direction into the screw head 4 to allow rotation. Theclearance surfaces 424 and 426 may frictionally engage when the base 410is rotated in a reverse direction to remove it from the screw head 414.

Frictional engagement of the thrust surfaces 406 and 408 due to rotationcauses the base 410 to be advanced linearly along the axis 412 into thescrew head 414. However, once the base 410 “bottoms out” by contact of alower surface 428 or a set point 430 with a rod 432 and the rod 432 isunbent and pushed downwardly as far as it will go into a channel or seatof the head 414, further rotation of the base 410 cannot result infurther linear movement of the base 410 within the head 414. Theinterlocking forms 402 and 404 thereafter are radially locked togetherand each turn or pass of the forms 402 and 404 is preferablysufficiently snug with respect to turns of the opposite interlockingform to prevent either form 402 or 404 from slipping or sliding radiallypast one another upon application of additional torque or withapplication of forces due to usage by the patient.

The various compound, complex, or non-linear interlocking formarrangements of the present invention are intended to resist splayingtendencies of the arms 432. In particular, each thrust surface 406 and408 of the interlocking forms 402 and 404 have a gripping, blocking orsplay resisting surface 434 or 436 respectively which is oriented insuch a direction as to resist splaying of the arms 432 of the screw head414 when the base 410 is rotated to a high degree of torque. On theexternal interlocking form 402, the splay resisting surface 434 isdirected generally toward or faces the axis 412. Conversely, on theinternal interlocking form 404, the splay resisting surface 436 isdirected generally away from or faces away from the axis 412. Each ofthe surfaces 434 and 436 in this manner wrap over or around the oppositeand block substantial radially relative movement there between. It isespecially noted that the surfaces 434 and 436 are extensions of theinterlocking forms 402 and 404 in an axial direction (that is parallelto the axis 412 or up and down as seen in FIG. 49 ). This axialextension is spaced away from the juncture of the interlocking forms 402and 404 with the base 410 and screw 4. It is foreseen that such anextension can take many shapes and configurations (some of which areshown herein) and may also functionally be depressions or grooves. Ineach case the paired interlocking forms, such as forms 402 and 404,overlap each other and are snug about each other so as to preventsubstantial relative radial slippage or movement between them during andafter assembly of the base 410 into the bone screw 4.

FIG. 50 illustrate a non-linear or compound thrust surface interlockingform arrangement 438 which is of a medial bead interlocking form type.The interlocking form arrangement 438 is a thrust surface 406 located ona plug 410 and internal interlocking form 404 with thrust surfaces 408within a head 414 of a bone screw 4. The thrust surfaces 406 and 408 arecontoured to provide complementary, interacting, splay resistingsurfaces 434 and 436 on the external and internal interlocking forms 402and 404 respectively. The external interlocking form 402 is providedwith a bead 440 on the thrust surface 406, and the internal interlockingform 404 is provided with a complementary channel or groove 442 formedinto the thrust surface 408. The illustrated thrust surfaces 406 and 408are substantially perpendicular to the axis 412; however, such surfacesmay alternatively be angled somewhat with respect to the axis 412 so asto slope downward or upward as the surface extends radially outward.

The bead 440 is located at a radius which is between or medial withrespect to the root 416 and crest 418 of the external interlocking form402. Similarly, the groove 442 is located at a radius which is medial tothe root 420 and crest 422 of the internal interlocking form 404. Theillustrated bead 440 and groove 442 are rounded and somewhat triangularin cross section. Alternatively, the bead and groove 440 and 442 couldbe pointed and triangular, squared off, or semicircular. It should alsobe noted that the bead and groove 440 and 442 could be replaced by amedial groove formed in the external interlocking form 402 on the thrustsurface 406 and a medial bead formed on the thrust surface 408 of theinternal interlocking form 404. An inwardly facing surface 444 of thebead 440 forms the splay resisting surface 434 thereof, while anoutwardly facing surface 446 of the groove 442 forms the splay resistingsurface 436 of the groove 442. Engagement of the splay resistingsurfaces 444 and 446, respectively of the bead 440 and groove 442,resists tendencies of the arms 432 of the screw head 414 to splay whenthe closure base 410 is rotated into the head 414.

FIGS. 51 to 59 illustrate further variations in the paired interlockingforms of the present invention. In each case the base closure and bonescrew, except as noted with respect to the interlocking forms, of thevariations shown in FIGS. 51 to 59 are essentially the same as thoseshown in FIG. 49 , so only differing detail of the interlocking formstructure will be described in detail and reference is made to thedescription given for FIG. 49 for the remaining detail.

In FIG. 51 , a guide and advancement structure 448 includes the externalinterlocking form 450 having an axially aligned shoulder or flange-likeshaped configuration when view in cross section in a plane passingthrough an axis of rotation 452. The interlocking form 450 has a thrustsurface 454 on a base 456. The structure 448 also has an internalinterlocking form 458 with a thrust surface 460 within the head 462 of abone screw 464. The internal interlocking form 458 has a root 466 and acrest 468, while the external interlocking form 450 includes a root 470and crest 472. The thrust surface 454 of the external interlocking form450 includes an axially oriented or cylindrical shoulder 474 which formsa splay resisting surface 476 thereof.

Similarly, the thrust surface 460 of the internal interlocking form 458includes a mating or complementary axially oriented or cylindricalshoulder 478 which forms a splay resisting surface 480. Engagement ofthe splay resisting surfaces 476 and 480 resists tendencies of the arms482 of the head 462 to splay when the plug or base 456 is rotated intothe head 462 and torqued tightly or at later times during usage. It isforeseen that a variation of the axial shoulder interlocking form wouldprovide shoulders at inclined angles (not shown) to the axis 412. Theillustrated splay resisting shoulder 474 is formed by a rectangularcross section bead 484 formed on the thrust surface 454 of the externalinterlocking form 450. Similarly, splay resisting shoulder 478 is formedby a somewhat rectangularly cross section shaped bead or foot portion486 adjacent a groove 488 for receiving bead 484 and formed in thethrust surface 460 of the internal interlocking form 458. Theinterlocking forms 450 and 458 have a general flange-like shapeconfiguration when viewed in cross section that is also some whatL-shaped with the beads 484 and 486 forming feet of the flange shapethat overlap and lock so as to prevent substantial radial movement ofthe arms 482 of the bone screw 464 relative to the closure plug base456. FIGS. 52 and 53 illustrate further variations of the axial shoulderinterlocking structure 490 and 508 respectively in the form of a roundedaxial bead interlocking form 492 shown in FIG. 52 and a shallow roundedaxial bead interlocking form 510 in FIG. 53 . The rounded axial beadinterlocking form 492 includes a rounded bead 493 projecting in adirection parallel to an axis 495. The bead 493 is formed on a thrustsurface 494 of an external interlocking form 496 and a rounded groove498 is formed on a thrust surface 500 of an internal interlocking form502. The bead 493 includes a splay resisting surface 504, while thegroove 498 also includes a splay resisting surface 506.

In a similar manner, the shallow rounded axial bead interlocking form508 includes a shallow rounded bead 510 formed on a thrust surface 512of an external interlocking form 516 and a shallow rounded groove 514formed on a thrust surface 517 of an internal interlocking form 518. Thebead 510 includes a splay resisting surface 520, and the groove 514includes a splay resisting surface 522. The surfaces 520 and 522 engageand abut to resist splaying or significant radial separation movementtherebetween.

FIG. 54 illustrates a radial bead embodiment of an implant 524 having aguide and advancement structure 526. The structure 526 includes arounded external and bead interlocking form 528 projecting radially froma base 530 and forming a crest 532. The bead interlocking form 528 has apair of splay resisting surfaces 536 facing generally toward an axis 534of rotation of the base 530. A complementary groove internalinterlocking form 538 is part of a screw head 540. The head interlockingform 538 has a pair of splay resisting surfaces 542 facing generallyaway from the axis 534. The structure 526 has the splay resistingsurfaces 536 and 542 on thrust surfaces 544 and 546 respectively of theinterlocking forms 528 and 538, as well as on clearance surfaces 548 and550 thereof. The illustrated radial bead interlocking form 524 is, insome ways, a double sided variation of the rounded axial beadinterlocking form of an earlier embodiment.

FIGS. 55 and 56 illustrate a scalloped or scooped embodiment structure572 including a pair of compound interlocking forms 552 and 554according to the present invention. The interlocking form 552 isscalloped and, in effect, an inversion of the shallow rounded beadinterlocking form similar to that of an earlier embodiment. Theinterlocking form 554 includes a shallow groove 556 formed in a thrustsurface 558 of the external interlocking form 552 of a base 560 and ashallow bead 562 formed on a thrust surface 564 of the interlocking form554 of a screw head 566. The groove 556 has a splay resisting surface568 which cooperates with a complementary splay resisting surface 570 ofthe bead 562.

Illustrated in FIG. 57 is another guide and advancement structure 600associated with a receiver member 601 and a closure member, such as aplug, 602 that is rotated into the receiver member 601. The structure200 includes a first interlocking form 605 and a second interlockingform 606 attached to the closure member 602 and receiver member 601respectively.

The first interlocking form 605 includes an arcuate upper surface 607with a gripping or locking section 608. The second interlocking form 606includes an arcuate lower surface 609 with a gripping or locking section610. The interlocking forms 605 and 606 also have respective lower orleading surfaces 614 and 615 respectively that are sufficiently spacedto allow rotation about the axis thereof, but sufficiently close to besnug and not allow substantial movement of the forms 605 and 606relative to each other in an axial direction without rotation.

FIG. 58 shows an alternative flange shaped embodiment of a guide andadvancement structure 630 in accordance with the invention. Thestructure 630 is mounted on a closure 631 and a receiver 632 so thatinterlocking forms 633 and 634, which are seen in cross section, arehelically mounted on the closure 631 and receiver 632 respectively.

The first interlocking form 633 is L or flange-shaped in cross sectionwith a vertically or axially extending foot portion 640 with a grippingsurface 641. The second interlocking form 634 generally complements thefirst and is also L or flange shaped except that a foot 643 thereof ismuch wider than the foot portion 640. The foot 643 has a gripping orwraparound surface 645 that abuts the surface 641 during assembly andresist radial movement between the receiver 632 and the closure 631.

Shown in FIG. 59 is another embodiment of a guide and advancementstructure 660 in accordance with the invention. The structure 660 isutilized with a receiver 661 and a closure or plug 662. The structure660 has first and second interlocking forms 663 and 664. The firstinterlocking form has an elongate wall 668 with a circular bead 669attached to an end thereof opposite the closure 662. The bead 669 hasopposed gripping surfaces 670 and 671. The second interlocking form 664is shaped to mate with and generally surround the first interlockingform 663 except sufficient clearance is provided to allow the closure662 to be rotated and advanced into the receiver 663 by slidingtangentially, but not radially. The second interlocking form 664 has acircular cross section channel 672 that receives the bead 669 and a pairof gripping surfaces 673 and 674 that engage and abut against the beadsurfaces 670 and 671.

It is foreseen in accordance with the invention that certain regions ofthe interlocking forms may be eased or removed to allow for easier usewhich still maintaining the primary objective of resisting radialmovement between the closure plug and the opposed arms of the bone screwto prevent splaying of such arms.

It is also seen in accordance with the invention that the axial alignedextension or depression on the described interlocking forms could insome cases be multiple in nature or formed by an undulating pattern.

Turning back to FIGS. 46-48 , the helically wound guide and advancementstructures 64 and 114 in the respective guide tools 9 and 10 are sizedand shaped to receive the mating guide and advancement structure 181 ofthe closure top 62 and align with the guide and advancement structure183 of the bone screw 4 to form a generally continuous helically woundpathway, but does not require locking between the closure top 62 and thetools 9 and 10, even when an interlocking flange form is utilized on theclosure top 62.

The guides 64 and 114 allow the closure top 62 to be rotated and thesurgeon to develop mechanical advantage to urge or drive the rod 8,while still outside or partially outside the bone screw 4, toward andinto the bone screw head 146. This is especially helpful where the rod 8is bent relative to the location of the vertebra 16 (which is sometimesthe case) to which the rod 8 is to attach and is not easily placed inthe bone screw head 146 without force and the mechanical advantageprovided by the guides 64 and 114. In particular, the guide andadvancement structures 64 and 114 on the respective tools 9 and 10 arelocated and positioned to align with the guide and advancement structure183 on the insides of the bone screw arms 150 and 151, as shown in FIG.42 and pass the closure top 62 therebetween while allowing the closuretop 62 to continue to rotate and to continuously apply force to the rod8, so as to aid in seating the rod 8 in the bone screw head 146.

Each closure top 62 also preferably includes a break-off head 186 thatbreaks from the cylindrical body 180 in a break-off region 187 upon theapplication of a preselected torque, such as 95 to 120 inch-pounds. Thebreak-off head 186 preferably has a hexagonal cross section facetedexterior that is configured to mate with a similarly shaped socket of afinal closure driving or torquing tool 190 described below. It isforeseen that different driving heads or other methods of driving theclosure top 62 can be utilized with certain embodiments of theinvention, such as non-break-off closure top designs.

Turning to FIGS. 60-62 , another example closure member 600 isillustrated. The closure member 600 includes a plug, base section orbase 602 and a break off head section 604 that breaks from the base 602at a preselected torque. It is foreseen that such a closure could bemade without a breakoff head and other structure could be added fortorquing or removing the base section, Furthermore, it is foreseen thatsuch a base both captures the rod and locks the rod as in the embodimentillustrated in FIGS. 60 to 62 or, alternatively, that the base couldjust capture the rod and a set screw could be used in a threaded bore inthe base to lock the rod in place. The base section 602 is provided withthe external interlocking form 402, as described above, which iscompatible with the internal interlocking form 404 of the bone screwhead 606. Both interlocking forms 402 and 404 are helically wound androtatably rateable together through rotation or turning of the closuremember 600 about the central axis 412 thereof. The head 608 includesstructure for positive engagement by an installation tool (not shown) toinstall the closure member 600 in the bone screw member 610. Thestructure that allows for installation of the illustrated break off head604 includes faces 612 forming a hexagonal shape or “hex” head toreceive a complementary hexagonally shaped installation driver or tool.The head 604 also includes a central bore 614 and a cross bore slot 616.The outer end of the head 604 is chamfered at 618, and the bore 614 isprovided with an interior conical countersink at 620. The region wherethe head 604 meets the base 602 is reduced in cross sectional thicknessto form a weakened breakaway or fracture region 622. The breakawayregion 622 is designed so that the head 604 separates from the base 602when a selected torque is applied by the installation tool, as isdiagrammatically illustrated by breaking away of the head 604 in FIG. 62. The base 602 is preferably provided with structure to facilitateremoval of the base 602 from the implant head 606, such as theillustrated removal bores 624. The bores 624 may be formed by drillingfrom a lower end surface 626 of the plug 602, since an upper end surface628 of the plug 602 is normally not accessible for drilling the bores624 prior to break-off of the head 604. It is foreseen that manydifferent types of removal devices or structures can be utilized withthe base such as: axially aligned bores with hex, torx or othermultifaceted cross-section, step down bores for engagement by an easyout, bores at the periphery or non axially aligned on the face of thebase, bores with a left handed thread or the like. Further. the samestructure used to torque the base on installation may be used to removethe base.

The base 602 is rotated into the receiving member of the bone screw head606 to clamp the fixation rod 608 therein for any of a variety ofsurgical purposes. In general, the rod 608 is used to fix the positionof a bone or portion of a bone, such as a plurality of vertebrae. Therod 608 may be anchored relative to some vertebrae and, in turn, used tosecure other vertebrae in desired positions or orientations or used toproperly align a series of vertebrae. It is generally required that theunion formed between the bone screw 610, closure 600 and the rod 608 bevery tight or snug to avoid relative movement therebetween. The fixationsystem 630 preferably employs structure that positively engages andseats the head 606 and/or the base 602 with respect to the rod 608, suchas a conical set point 632 formed on the bottom surface 626 of the base602 which engages the rod 608. The point 632 positively “bites” into thesurface of the rod 608 to help prevent rotational or axial movement ofthe rod 608 relative to the screw 610. Alternatively or in combinationwith a point 632, other structures may be used to positively engage theclosure plug 602 with the rod 608, such as a sharp edged coaxial ring(not shown) having a V-shaped cross section formed on the lower surface626 of the base 602 or point extending upwardly from the channel.

The present invention is not intended to be restricted to a particulartype of bone screw or bone screw closure mechanism. In the presentembodiment, a polyaxial type bone screw 4 is utilized wherein the shank148 is locked in position by direct contact with the rod 8. It isforeseen that the tool set 2 of the present invention can be used withvirtually any type of bone screw, including fixed monoaxial andpolyaxial bone screws of many different types wherein the head is lockedrelative to the shank by structure other than in the manner described inthe illustrated embodiment.

With reference to FIGS. 22-25 , the multi-purpose installation tool 12of the tool assembly 1 of the invention includes an upper translationnut 202 rotatably and free wheelingably attached to a lower guide toolstabilizer or support sleeve 204. The sleeve 204 has an innersubstantially cylindrical surface 205 defining a substantially hollowpassageway 206 sized and shaped to slidingly receive an end tool 9 or anintermediate tool 10 therein. Alternatively, is foreseen that the sleevecould have an inner and outer planar surface. The sleeve 204 is elongateand includes a receiving end 207, a substantially cylindrical outer body208 and a translation nut attachment end portion 210 disposed oppositethe receiving end 207. The receiving end 207 not only functions toreceive the guide tool 9 or 10 into the sleeve 204, but also as apressing block 218 for contacting the flexible flap or spring tang 38and as a pressing end 207 for contacting the rod 8 and translating therod 8 toward the bone screw head 146 when the multi-purpose installationtool 12 is installed on the guide tool 9 or 10, as will be discussedmore fully below.

The cylindrical body 208 further defines a slotted U-shaped or C-shapedchannel 212 that opens radially at an opening 213 and also opens at thereceiving end 207 and extends substantially along a length of the body208 to a location 214 spaced from the nut attachment end portion 210.The channel opening has a side-to-side width 216 sized to receive theback wall tang portion or flexible flap 38 of the end guide tool 9therethrough, when aligned therewith. For example, with reference toFIG. 38 , the multi-purpose installation tool 12 is shown partiallyremoved from an end guide tool 9 and deploying the tang 38 after thebone screw has been inserted. Because of the substantial length of thechannel 212 as defined by the location 214 and because of the channelwidth 216, the multi-purpose installation tool 12 can be removed, turned180° and reattached to the end guide tool 9 thereby providing accessthrough the channel opening 213 for protrusion of the back wall tangportion or flap 38 of the end guide tool 9. The flap 38 is thus notencumbered or restricted by the tool 12 during the rod pushingapplication and the flap 38 can be flexed outwardly by a rod 8 (notshown) or other forces, when the devices are assembled in thisconfiguration.

Disposed flush to the lower sleeve end 207 and rigidly attached to theinner cylindrical surface 205 is the solid guide tool alignment andtang/rod pressing block 218. The block 218 has a substantially smooth,planar and rectangular surface 220 facing inwardly radially from theinner surface 205. The block 218 also follows the curve of thecylindrical surface 220 at a surface 222 thereof. Thus, as shown in FIG.24 , the block 218 has a segment shape when observed from a bottom planview. The term segment used herein is defined as the part of a circulararea bounded by a chord and an arc of a circle cut off by the chord.This segment shape of the block 218 provides a mechanical advantage forcompressing the flexible flap 38 flush with the end guide tool 9 and foradvancing the rod 8 into the bone screw 4 with the multi-purposeinstallation tool 12 which will be discussed more fully below.

The flat, rectangular surface 220 provides structure for installing theguide tool 9 or 10 in a mating and desired alignment with respect to themulti-purpose installation tool 12. For example, with respect to theguide tool 10, a preferred alignment is that the rear wall 81 of thetool 10 be disposed adjacent to the surface 220 when inserting the tool10 into the multi-purpose installation tool 12. Then, the tool 10 isslid into the multi-purpose tool sleeve 204, with the block 218preventing axial rotation of the tool 10 with respect to the sleeve 204,and resulting in the preferred alignment of the opening 79 and thepass-through slot 11 of the tool 10 and the U-shaped channel 212 of themulti-purpose tool in this application.

With respect to the end guide tool 9, the block 218 with the planarsurface 220 provides for the insertion of the tool 9 in a first,installation tang containing position or a second, rod pushing position.When utilizing the assembly 1 of the invention to install a bone screw4, it is advantageous for the flexible back wall portion or tang 38 ofthe tool 9 to be fully restrained by the multi-purpose installation tool12 and for the walls 68 and 69 to be locked in a non-splayable oranti-splay position. Therefore, in the first, bone screw installationtang containing position, the multi-purpose installation tool 12 isinserted onto the tool 9 with the back wall 28 of the tool 9 disposedadjacent to the sleeve surface 220. Then, the tool 9 and the sleeve 204are attached with the block 218 preventing axial rotation of the tool 9with respect to the multi-purpose installation tool 12. This results inthe preferred alignment wherein the flexible back wall portion or tang38 is disposed adjacent to the multi-purpose tool sleeve 204 andcontained and disposed opposite the U-shaped channel 212. After the bonescrew 4 is installed and it is desired to install the rod 8 in two ormore bone screws 4, the multi-purpose installation tool 12 is removedfrom the end guide tool 9 and replaced thereon with the slot 44 andchannel openings 40 and 94 adjacent to and facing the alignment block218.

The translation nut 202 of the multi-purpose installation tool 12 issubstantially cylindrical in shape and is shown with outer grooves 223to aid a surgeon in handling the multi-purpose installation tool 12 androtating the nut 202. The nut 202 further includes an inner cylindricalsurface 224 defining an inner substantially cylindrical passage 226communicating with the passage 206 of the sleeve 204. The inner surface224 further includes a helical guide and advancement structure as shownby a V-shaped thread 228 that is configured to mate with the guide andadvancement structure 50 of the end guide tool 9 or the guide andadvancement structure 93 of the intermediate guide tool 10.

With reference to FIG. 25 , the inner cylindrical surface 224 extendsfrom an upper open end 230 of the translation nut 202 to an annularseating surface 232 extending radially outwardly and perpendicular tothe cylindrical surface 224. As will be discussed more fully below, thesurface 224 with associated thread 228 is of a length that provides anequivalent translation distance of the multi-purpose installation tool12, and in particular the tang/rod pressing block 218, with respect tothe guide tool 9 or 10 such that the pressing block 218 can be used togradually push the rod 8 toward the bone screw 4 for the entiretranslation distance by rotating the nut 202 which can be continueduntil the rod is fully seated in the head of the bone screw.

Also with reference to FIG. 25 , at the annular seating surface 232, thesleeve 204 is in sliding contact with the nut 202. A lower portion 234of the nut 202 further defines a second inner cylindrical surface 236 ofgreater diameter than the surface 224. The surface 236 has a diameterslightly greater than a diameter of the sleeve 204 and is configured toslidingly receive the sleeve 204 into the nut 202 along the surface 236.The nut 202 further defines an annular recess or groove 238 configuredto receive a pin 240 rigidly fixed to the sleeve 204. The pin 240 may beaccessed for attachment and removal from the sleeve 204 through anaperture 242 disposed in the translation nut 202. The pin 240 slidinglymates with the nut 202 within the recess 238, keeping the nut 202 andsleeve 204 in an attached but freely rotatable relation.

With reference to FIGS. 26-28 , the driver 14 of an assembly 1 accordingto the invention includes a handle 250, a guide tool fastener or nut252, and an elongate cylindrical stem or shaft 254 having a lowercylindrical portion 255 integral with a bone screw engager shown as asocket 256. The socket 256 is configured to mate with the upper part ofthe bone screw shank 154. The shaft 254 with attached socket 256 isreceivable in and passes through the interior of the guides 9 and 10,such as the channel 80 of the guide tool 10. The lower portion 255 has aslightly smaller diameter than a diameter of the remainder of the shaft254, this smaller diameter provides for adequate clearance of theportion 254 from the guide and advancement structures 64 and 114 whenthe shaft 254 is installed within the interior of the respective guidetools 9 and 10. The stem or shaft 254 is rigidly attached to the handle250 and coaxial therewith. Both the handle 250 and the guide toolfastener 252 include outer grooves 258 and 259 respectively, about outercylindrical surfaces thereof to aid in gripping and rotating therespective components.

The guide tool fastener 252 is a substantially hollow cylinder disposedin coaxial relationship with the handle 250 and the shaft 254. Thefastener has a threaded inner cylindrical surface 262 disposed at alower portion 263 thereof, the threaded surface 262 configured to matewith the guide and advancement structure 50 of the end guide tool 9 orthe guide and advancement structure 93 of the intermediate guide tool10. The fastener 252 is disposed on the driver 14 between an annularsurface 264 of the handle 250 and the pin 46 that is fixed to the shaft254 and extends laterally therefrom.

The driver 12 further includes a lateral pin 266 projecting radiallyoutwardly from a cylindrical surface 268 adjacent the handle 250. In theembodiment shown, the cylindrical surface 268 is integral with thehandle 250 and fixedly attached to the shaft 254. The pin 266 isdisposed within an annular recess 270 defined by the cylindrical surface268, and surfaces of the fastener 252, including an upper seatingsurface 272, a lower seating surface 274 and an inner cylindricalsurface 276. The pin 266 disposed in the recess 270 allows for bothrotational and axial or vertical translational movements of the fastener252 with respect to the shaft 254. Thus, as shown in FIG. 26 , thefastener 252 is rotatable about an axis C. Furthermore, the fastener isslidable along the axis C between the annular surface 264 and the pin46, with FIG. 26 showing a first or unattached position with thefastener 252 in contact with the annular surface 264 and FIGS. 27 and 28showing a second, engagement position, with the fastener 252 partiallycovering, but not contacting the pin 46, with the pin 266 abutting theupper seating surface 272 prohibiting further downward or vertical(axial) translational movement of the fastener 252 with respect to theshaft 254.

As stated previously herein, the pin 46 is configured for slidingengagement with both the slot 44 of the guide tool 9 and the slot 88 ofthe guide tool 10 when the driver shaft 254 is disposed in an interiorof the guide tool 9 or 10. When the pin 46 is received in the slot 44 orthe slot 88, any relative rotational movement between the guide tool 9or 10 and the driver 14 is prevented, but the driver is free to slideaxially with respect to the guide tool 9 or 10. When the fastener or nut252 is slid into the second position shown in FIGS. 27 and 28 and thefastener is mated with the guide and advancement structure 50 of the endguide tool 9 or the guide and advancement structure 93 of theintermediate guide tool 10 by rotating the fastener 252 to a locationadjacent to the pin 46, with the pin 266 in contact with the upperseating surface 272, relative axial movement between the driver 14 andthe guide tool 9 or 10 is also prevented.

With reference to FIGS. 1 and 29-35 , a three-component assembly 1according to the invention including the guide tool 9, the multi-purposeinstallation tool 12 and the driver 14 may be assembled as follows: Theguide tool 9 shown with attached bone screw 4 is inserted into themulti-purpose installation tool 12 with the upper end 43 being insertedinto the receiving end 207 of the multi-purpose installation tool 12.With respect to the assembly shown in FIGS. 29-31 , illustrated is aparticular assembly wherein the multi-purpose installation tool 12 isbeing utilized as a support or stabilizer for the end guide tool 9during installation of the bone screw 4 into the vertebra 16,specifically, to contain and compress the tang 38 and to provide extrasupport to the walls, such as walls 68 and 69 of tool 9. Thus, the guidetool 9 is received into the multi-purpose installation tool 12 with therear wall 28 facing the alignment block 218 as shown in FIG. 29 .

As the guide tool 9 is received into the multi-purpose installation tool12, rotational movement is prevented by the alignment block 218 insliding contact with the flat surfaces 28 of the guide tool 9. Thetranslation nut 202 is then rotated clock-wise as viewed from the topend 230 and shown by the arrow X, with the thread 50 of the guide tool 9mating with the thread 228 disposed on the inner surface 224 of thetranslation nut 202. The translation nut 202 is preferably rotated untilthe upper end 43 of the guide tool 9 is positioned outside of the bodyof the nut 202 with a few of the threads 50 exposed as shown in FIGS. 30and 31 . Furthermore, the sleeve 204 cannot be translated beyond the pin67 that stops the sleeve near the rod abutment recess 61 disposed nearthe end of the guide tool 9. During rotation of the translation nut 202,the guide tool 9 is held in a preferred bone screw installation positionand any rotational movement of the tool 9 is prevented by the alignmentblock 218 in contact with the co-planar back walls or facets 71 of theguide tool 9 as well as the planar back surface of the tang 38. Asillustrated in FIGS. 30 and 31, when the guide tool 9 is fully installedin the multi-purpose installation tool 12 in this first or bone screwinstallation position, the flexible back wall portion or flap 38 iscompressed and retained in place between the side walls 32 and 33 by thealignment block 218.

When the multi-purpose installation tool 12 is used as a rod pusher withthe guide tool 9 as shown in FIGS. 38 and 41 , the multi-purposeinstallation tool 12 is preferably used first as an end guide toolstabilizer and tang 38 container, as already described herein, and thusmust first be removed by rotating the translation nut 202counter-clockwise until the multi-purpose installation tool 12 isdisengaged from the end tool guide 9 thereby deploying the tang 38.Thereafter, the multi-purpose installation tool 12 is removed andreplaced on the guide tool 9 with the slot 44 and channel openings 40and 94 adjacent to and facing the alignment block 218. As themulti-purpose installation tool 12 reinserted onto the guide tool 9,rotational movement is prevented by the alignment block 218 in slidingcontact with the flat surfaces 47 and 48 of the guide tool 9. Thetranslation nut 202 is then rotated clock-wise as shown by the arrow X(FIG. 29 ), with the thread 50 of the guide tool 9 mating with thethread 228 disposed on the inner surface 224 of the translation nut 202.Similar to what is shown in FIGS. 30 and 31 , the translation nut 202 isrotated clockwise as shown by the arrow X, until the upper end 43 of theguide tool 9 is positioned outside of the body of the nut 202 with someof the threads 50 exposed. During rotation of the translation nut 202,the guide tool 9 is held in position and any rotational movement of thetool 9 is prevented by the alignment block 218 in contact with theco-planar front walls or facets 70 of the guide tool 9. When themulti-purpose installation tool 12 is used in this second or rod pushingposition, the flexible back wall tang portion or flap 38 is notobstructed by the sleeve 204 of the multi-purpose installation tool 12and may spring out or be further pushed out through the opening 213 ofthe U-shaped channel 212.

An assembly 1 according to the invention may also include theintermediate guide tool 10 in the place of the guide tool 9 as shown inFIGS. 40-42 . Because the intermediate guide tool 10 includes apass-through slot 111 rather than a flexible back wall tang portion 38,the alignment between the multi-purpose installation tool 12 and theguide tool 10 may be the same during bone screw installation as for thepushing of the rod 8. Therefore, the tool guide 10 may be inserted intothe multi-purpose installation tool 12 with either the rear wall 81 orthe slot 88 adjacent to and facing the alignment block 218.

Similar to the discussion herein with respect to the guide tool 9, asthe guide tool 10 is inserted into the multi-purpose installation tool12, rotational movement is prohibited by the alignment block 218 insliding contact with either the rear wall 81 or the coplanar surfaces 91and 92 of the guide tool 10. The translation nut 202 is then rotatedclock-wise as viewed looking toward the top 87 of the tool 10, with thethread 93 of the guide tool 10 mating with the thread 228 disposed onthe inner surface 224 of the translation nut. Similar to what is shownin FIGS. 30 and 31 , the translation nut 202 is rotated until the upperend 87 of the guide tool 10 is positioned outside of the body of the nut202 with some of the threads 93 exposed. During rotation of thetranslation nut 202, the guide tool 10 is held in position, withrotational movement of the tool 10 being prevented by the alignmentblock 218 in contact with the co-planar front walls or facets 109 or theco-planar rear walls or facets 110 of the guide tool 10.

Further discussion of the assembly 1 in this application will bedirected toward the end guide tool 9 shown in the drawings. Unlessspecifically stated otherwise, the intermediate guide tool 10 can beutilized in similar fashion to what is being described herein withrespect to the end guide tool 9.

With reference to FIGS. 1 and 32-35 , after installation of themulti-purpose installation tool 12 to the guide tool 9, the driver 14 isinserted into the guide tool 9/multi-purpose installation tool 12combination by inserting the socket end 256 into the end 43 of the guidetool 9 and sliding the shaft 254 into the interior of the guide tool 9until the socket end 256 contacts and surrounds the upper part of theshank 154 of the bone screw 4 as shown in FIG. 35 . As the shaft 254 isbeing inserted into the guide tool 9, the pin 46 on the shaft 254 of thedriver 14 is aligned with and slid into the slot 44 of the guide tool 9.In order to more easily view the pin alignment process, the guide toolfastener 252 is placed in the first or unattached position with thefastener 252 in contact with the annular surface 264 as shown in FIG. 32. Also as shown in FIG. 32 , preferably, the pin 46 is slid to aposition disposed substantially within the slot 44 when the socket end256 engages the shank 154 of the bone screw 4. The guide tool fasteneror nut 252 is then rotated clockwise as viewed from the handle andillustrated by the arrow Y in FIG. 33 , from the first unattachedposition toward the second engaged position, mating the thread 50located near the end 43 of the guide tool 9 with the inner threadedsurface 262 of the nut 252 of the driver 14. If, after the fastener 252is rotated to a hand-tightened position, and a gap or space remainsbetween the fastener 252 and the translation nut 202, as shown in FIG.33 , the translation nut 202 may then be rotated counter-clockwise asshown by an arrow Z in FIG. 33 , and hand-tightened until thetranslation nut 202 abuts against the fastener 252, as shown in FIG. 34. The assembly 1 is then fully assembled and may be used to install thebone screw 4 into the vertebra 16 as will be described more fully below.Thereafter, the driver 14 may be removed by rotating the fastener 252 ina counter-clockwise direction (arrow Z) and sliding the shaft 254 out ofthe multi-purpose installation tool 12 through the open end 230.

Another tool used in implanting a spinal rod 8 is an antitorque tool 300illustrated in FIGS. 44 and 45 and further shown in FIG. 44 with aclosure top installation tool 302 engaging the break-away portion 186 ofthe closure top 62. The closure top installation tool 302 includes anupper handle portion 303 and a lower, closure top engagement portion 304configured to mate with and rotate the closure top 62.

The antitorque tool 300 is also preferably used with a closure toptorquing tool 305, shown in FIGS. 47 and 48 . The tool 305 is used totorque and set the closure top 62, so it is snug against the rod 8, andthereafter break away the break-off head 186 in the manner shown in FIG.48 . The torquing tool 305 is preferably in the form of a socket asshown in the drawings to allow for adequate tightening of the closuretop 62 and also ease in removal of the break-off head 186 as shown inFIG. 48 .

The antitorque tool 300 includes a tubular hollow shaft 306 that issized and shaped to be slidably received over the installation tool 302and also the torquing tool 305. The shaft 306 has a lower end portion308 that has a pair of diametrically spaced, curved bridges 310. Each ofthe bridges 310 is sized and shaped to fit over the rod 8, shown inFIGS. 47 and 48 . When in place, as illustrated in FIG. 47 , theantitorque tool 300 allows a surgeon to counter torque applied by thetorquing tool 305, when applying torque to and breaking away thebreak-off head 186. The antitorque tool 300 also has an upper handle 316disposed perpendicular to the shaft 306 and having an opening 318through which the installation tool 302 and the torquing tool 305 passesin the manner suggested by FIGS. 46-48 .

In use, the previously described tools are utilized to attach one ormore rods 8 to the human spinal column 6. The procedure is begun byselection of a bone screw 4 in accordance with the size of the patient'svertebra 16 and the requirements of the spinal support needed. Bonescrews 4 having a rotatable or polyaxial head 146 are preferred but notrequired for the procedure, as such allow relatively easy adjustment ofthe rod 8 in the tools 9 and 10 during placement and for movement of thetools 9 and 10, as described below. The bone screw 4 is also preferablycannulated so as to be receivable over and guided by a guide pin 355 asdiscussed more fully below.

A relatively small incision, such as an incision 350 in the skin 20 isthen made for each bone screw 4 to be used. Preferably, the incisionsare sized so as to snugly receive the tools of the invention. Theincisions 350 are stretched into a round shape with a circumferenceequal to or just slightly larger than the multi-purpose installationtool 12. The skin 20 is relatively flexible and allows the surgeon tomove the incision 350 around relative to the spine 6 to manipulate thevarious tools and implants, as required. In some cases, two screws canbe inserted through one or the same incision.

With reference to FIG. 36 , a drill (not shown) is utilized to form afirst guide bore 366 in a vertebra 16 under guidance of non invasiveimaging techniques, which procedure is well known and established. Thethin pin or guide wire 355 is then inserted in the first guide bore 366.This first guide bore 366 and associated thin pin 355 function tominimize stressing the vertebra 16 and provide an eventual guide for theplacement and angle of the bone screw shank 148 with respect to thevertebra 16.

The guide bore 366 is enlarged utilizing a cannulated drilling tool ortap 360 having an integral or otherwise attached cannulated and threadedbit 362 with an outer surface sized and shaped to correspond to the sizeand shape of the chosen threaded bone screw 4. The drilling tool 360cooperates with a cylindrical holder or sleeve 368 having an innersurface in slidable mating arrangement with the tool 360 and being heldin a position substantially co-axial therewith. The holder 368 is sizedand shaped to fit within the incision 350 and prevents soft tissues frombeing rolled up in the threaded bit 362 as it is rotated. The tool 360further includes a handle 370 fixedly attached to the tool 360 locatedat an end portion 372 thereof and of a size and shape for rotating thebit 362 along the pin 355 and into the first bore 366.

With the pin 355 still in place, the enlargement of the guide bore 366begins by threading the thin pin 355 through the end of the tap andinserting the holder 368 into the incision until the holder comes intocontact with the vertebra 16. The drill bit 362 is advanced downwardalong the pin 355 until the drill bit 362 comes into contact with thevertebra 16. The tool 360 is then rotated within the holder 368 usingthe handle 370, driving the bit 362 along the pin 355 until a full sizedbore 380 is drilled to a depth desired by the surgeon. During drilling,the holder 368 remains stationary, shielding the surrounding tissue fromthe rotational movement of the bit 362 and tool 360.

The tool 360 is then removed by rotating the bit 362 in reverse untilthe bit 362 is outside the bore 380. The tool 360 is then removed fromthe holder 368, followed by the removal of the holder 368 through theincision 350.

Before placing the bone screw 4 in the vertebra 16, the bone screw 4 ispreferably joined to an associated guide tool 9 or 10, an associatedmulti-purpose installation tool 12, and an associated driver 14. It ispossible, but typically not desirable, to join a guide tool 9 or 10 tothe bone screw 4 after the installation of the bone screw 4 to thevertebra 16. There also may be instances wherein it is desirable to jointhe bone screw 4 to an associated guide tool 9 or 10, but not to themulti-purpose installation tool support 12 or the driver 14 until afterthe bone screw 4 is installed in the vertebra 16, if at all.Furthermore, the driver 14 may be used with a guide tool 9 or 10 withoutthe multi-purpose installation tool 12. However, it is preferable toutilize the multi-purpose installation tool 12 during installation of abone screw 4 into the vertebra 16 as the tool 12 provides mechanicaladvantage and aids in preventing inadvertent splaying of side walls 32and 33 of the end guide tool 9 and legs 102 and 103 of the intermediateguide tool 10.

The attachment structure 124 of the intermediate guide tool 10 is joinedto a bone screw 4 by first rotating the tool 10 relative to the bonescrew 4 so that the legs 102 and 103 are positioned as shown in FIGS. 17and 18 , with the facets 167 and 177 of the head 146 disposed betweenthe guide tool legs 102 and 103, and with the facet 167 adjacent the leg102 and the facet 177 adjacent the leg 103, thereby aligning the groove158 with the large pin 126 and the groove 168 with the large pin 130. Aslight splaying of the legs 102 and 103 is possible during alignmentwith the head arms 150 and 151.

The head 146 is then twisted into place by rotating the tool 10 axiallyin a clockwise direction as shown by the arrow T in FIGS. 18 and 19 .

The twist-on procedure described herein with respect to the attachmentstructure 124 of the intermediate tool 10 is also followed with respectto the end guide tool 9 attachment structure 72. As previously statedherein, the attachment structure 72 is substantially similar to theattachment structure 124 of the intermediate tool 10, with the onlydifference being that the end guide tool 9 includes a flexible back walltang portion 38 rather than the pass-through slot 111 of theintermediate guide tool 10.

After the bone screws 4 have been attached to the guide tools 9 and 10,a multi-purpose installation tool 12 is preferably attached to each ofthe guide tools 9 and 10. With respect to each of the intermediate guidetools 10, the multi-purpose installation tool 12 is preferably installedas follows: The rear wall 81 of the tool 10 is positioned adjacent tothe surface 220 and the tool 10 is inserted into the hollow passage 206and slid into the rod pusher sleeve 204 until the end 87 contacts thetranslation nut 210, with the block 218 preventing axial rotation of theguide tool 10 with respect to the multi-purpose installation tool 12,and resulting in the preferred alignment of the sleeve slot 11 and theopening 79 of the tool 10 with the U-shaped channel 212 of themulti-purpose installation tool 12. However, because the slot 11 is apass-through slot, the alignment of the guide tool 10 with respect tothe multi-purpose installation tool 12 is not critical to processesaccording to the invention. Therefore, in most instances the rear wall81 of the tool 10 may also be positioned opposite the surface 220 uponentry into the multi-purpose installation tool 12.

The translation nut 202 is then rotated with the thread 228 of the nut202 mating with the thread 93 of the tool 10. The nut 202 is rotated ina clockwise direction as illustrated by the arrow X in FIG. 29 until theend 87 is disposed outside of the nut 202 and positioned similar to whatis shown with respect to the multi-purpose installation tool 12 and endguide tool 9 assembly shown in FIGS. 30 and 31 . The abutment pin 118prevents further rotation of the nut 202 and advancement of the sleeve204 beyond the pin 118.

As shown in FIGS. 29-31 , the end guide tools 9 are similarly equippedwith multi-purpose installation tools 12. In order to compress the tang38 during installation of a bone screw 4 into a vertebra 16, the tool 9is received into the multi-purpose installation tool 12 with the backwall 28 of the tool 9 disposed adjacent to the surface 220. Then themulti-purpose installation tool 12 is slid onto the tool 9 until the end43 contacts the translation nut 202, with the block 218 preventing axialrotation of the tool 9 with respect to the multi-purpose installationtool 12, and resulting in the preferred alignment wherein the flexibleback wall tang portion or flap 38 is disposed adjacent to the guide toolsleeve 204 disposed opposite the U-shaped channel 212. The translationnut 202 is then rotated with the thread 228 of the nut 202 mating withthe thread 50 of the end guide tool 9. The nut 202 is rotated in aclockwise direction as illustrated by the arrow X in FIG. 29 until theend 43 is disposed outside of the nut 202 and positioned as shown inFIGS. 30 and 31 , but not beyond the pin 67.

The driver 14 is then installed into the guide tool 9 as shown in FIGS.32-35 and as follows: The driver 14 is first prepared for ease ofinsertion by placing the guide tool fastener 252 in the first orunattached position with the fastener 252 in contact with the annularsurface 264 of the driver 14 as shown in FIG. 32 . Then, the driver end256 is inserted into the guide tool 9 at the end 43 with the stem 254being slid into the guide tool 9 with the pin 46 aligned with thechannel 39 until coming to a stop with the pin 46 disposed in the slot44 and the bone screw engager 256 in contact with the bone screw uppershank 154. A slight rotation or jiggling of the bone screw shank 148 maybe required for the hex socket of the bone screw engager 256 to becomepositioned in operational engagement with the hex shaped upper shank154. The guide tool fastener or nut 252 is then moved downward andtoward the end 43 and then rotated clockwise as viewed from the handle250 and illustrated by the arrow Y in FIG. 33 , mating the thread 50disposed near the end 43 of the guide tool 9 with the inner threadedsurface 262 of the nut 252 of the driver 14. The nut 252 is rotated inthis clock-wise fashion and hand-tightened until further translation ofthe nut 252 along the guide tool 9 is prevented by the pin 266 abuttingthe upper seating surface 272.

If, after the fastener 252 is rotated to a hand-tightened position, anda gap or space remains between the fastener 252 and the translation nut202 as shown in FIG. 33 , the translation nut 202 is rotatedcounter-clockwise as shown by the arrow Z in FIG. 33 , andhand-tightened until the translation nut 202 abuts against the fastener252 as shown in FIG. 34 . The assembly 1 is now ready for bone screwinstallation into the vertebra 16.

The driver 14 is installed into the intermediate guide tool 10 andmulti-purpose installation tool 12 assembly in steps similar to thatdescribed above with respect to the end guide tool 9.

A series of bone screws 4 are installed in each vertebra 16 to beattached to the rod 8 by inserting each of the assemblies 1 through theskin incision 350 as shown in FIG. 37 . The screw 4 is then rotated anddriven into the tapped bore 380 with the surgeon holding and rotatingthe assembly 1 with the driver handle 250, thereby rotating the entireassembly 1 as one unit until the shank 148 is disposed at a desireddepth in the tapped bore 380 of the respective vertebra 16. Preferably,the shank 148 is also cannulated to receive the pin 355, providingadditional guidance for installation of the bone screw 4 into thevertebra 16.

After a specific bone screw 4 is installed, the driver 14 is removedfrom either the guide tool 9 or 10 by rotating the fastener 252 in acounter-clockwise direction (illustrated by the arrow Z in FIG. 33 ) andsliding the shaft 254 towards the open end 230 of the multi-purposeinstallation tool 12 and pulling the driver 14 out of the assembly 1 bythe handle 250.

With respect to the end guide tools 9, the multi-purpose installationtool 12 is then removed by rotating the translation nut 202counter-clockwise until the thread 228 disposed on the inner surface 224of the translation nut 202 is disengaged from the thread 50 of the tool9. The multi-purpose installation tool 12 is then slid off of the tool 9deploying the flexible flap 38, as shown in FIG. 38 . If desired at thisjunction of a process according to the invention, the multi-purposeinstallation tool 12 many then be rotated 180 degrees and replaced onthe tool 9 with the slot 44 and the channel openings 40 and 94 alignedadjacent to and facing the alignment block 218 of the multi-purposeinstallation tool 12 for a rod pushing application. The translation nut202 is then rotated clockwise as illustrated by the arrow X in FIG. 29 .In this rod pushing position, the flexible tang 38 is extendible intothe U-shaped channel 212 of the multi-purpose installation tool 12.

For each bone screw 4, an associated guide tool 9 or 10 extends throughthe skin 14, as illustrated in FIG. 39 . An end guide tool 9 is locatedat each end of the series of bone screws 4 and an intermediate guidetool 10 is located on each intermediate bone screw 4.

In order to install a rod 8 in two or more bone screws 4, it may not benecessary to equip each guide tool 9 or 10 with a multi-purposeinstallation tool 12. For example, with reference to FIG. 40 , for aparticular procedure, it may be desirable to utilize only onemulti-purpose installation tool 12 with a tool set 2 according to theinvention. In the process illustrated by the FIG. 40 , the multi-purposeinstallation tools 12 have been removed from both of the end guide tools9 and both of the intermediate guide tools 10 after which a rod 8 hasbeen inserted and a multi-purpose tool 12 reattached to one tool 10.Some pushing of the rod may be accomplished by just extending a rod ortool down the central channel of the guide tools 9 and 10 whenmechanical advantage is not required to move the rod 8. As required bythe surgeon, one or more multi-purpose installation tools 12 may beadded or removed at any time during the course of the rod pushing orreducing procedure.

With reference to FIG. 39 , prior to installation of the rod 8, the endguide tools 9 are turned or rotated so the channels 55 therein face oneanother and the intermediate guide tools 10 are aligned so thepass-through slots 111 align with the channels 55.

With reference to FIG. 40 , the rod 8 has been inserted diagonallythrough one of the end skin incisions 350 with the adjacent end guide 9pushed to the side, so that one of the rod ends 59 first passes throughthe slots 111 in the intermediate guide tools 10 and then into thechannel 55 of one of the guide tools 9. Back muscle tissue separateseasily here to allow the upper insertion of the rod 8 and can be furtherseparated by finger separation or cutting through one of the incisions350, if required.

After initial insertion, the remaining opposed end 59 of the rod 8 ispositioned in the channel 55 of the end guide tool 9 that is locatednext to the insertion point of the rod 8. Manipulation of the rod 8 inthe channels 55 is aided by the back wall tang portions or flexibleflaps 38 of the guide tools 9 which may also be moved like a joy-sticktoward or away from each other by the surgeon. Furthermore, once the rod8 is disposed within the channels 111 and 55, the back wall portions orflaps 38 resiliently bias against the rod ends 59, substantially holdingand containing the rod 8 in place between the end guide tools 9 of thetool set 2. The reason that the tangs 38 are needed is that the rod 8extends beyond the end bone screws 4 and the end guide tool 9 arelocated on the end bone screws 4. Also, the rod may tend to slip out ofone end screw head. When the rod is spaced above the bone screws 4, theguide tools 9 can be manipulated to be spaced farther apart to receivethe rod 8 therebetween, but as the rod 8 nears the bone screws 4, theguide tools 9 cannot be manipulated enough to compensate so the rod 8must extend beyond the bodies of the guide tool 9. Therefore, the tangs38 allow the rod 8 to be controlled and positioned outwardly of the endbone screws 8. Moreover, the position of the rod 8 is controlled byequal pressure applied by the tangs 38 so that the rod 8 extends pastthe bone screws 4 approximately an equal amount on each side.

Also with reference to FIGS. 40 and 41 , once the rod 8 is positioned inthe guide tools 9 and 10, the multi-purpose installation tool 12 may beutilized to push the rod 8 toward the bone screw 4, normally whenmechanical advantage is needed to seat the rod 8 in the bone screws 4.This is accomplished by rotating the translation nut 202 in a clockwisedirection (as viewed from above the skin 20), thereby translating thesleeve 204 in a downward direction toward the bone screw 4, with theguide tool alignment block 218 abutting and pushing against the rod 8.

As shown in FIG. 40 , it may also be desirable to simultaneously orthereafter push the rod 8 toward the screw 4 of one or more guide tools9 and 10 utilizing the closure top installation tool 302 pushing againsta closure top 62 that in turn pushes against the rod 8. In particular, aclosure top 62 is placed in the elongate top to bottom channelassociated with the guide tools 9 and 10, preferably by entry from theside such as into the channel opening 40 of the guide tool 9 oralternatively into the channel 39 through the top end 43 of the guidetool 9. If the guide tool 9 or 10 has the multi-purpose installationtool 12 attached, the closure top 62 can be placed into the guide toolby side insertion into the U-shaped channel 212. The closure topinstallation tool 302 is then inserted into the top end 43 and throughthe channels disposed within the guide tool 9, until the engagementportion 304 mates with a cooperating aperture disposed in the break-offhead 186. The closure top 62 is then driven or pushed under manualcontrol of the surgeon by use of the installation tool 145 toward therod 4.

With reference to FIG. 42 , near the bottom of the guide tools 9 and 10,such as near the end 112 of the intermediate tool 10 and the bottom 36of the back wall 28 of end guide tool 9, the closure top 62 engages thehelically wound guide and advancement structures 64 and 114 ofrespective guide tools 9 and 10. The tools 302 and mated closure tops 62are then rotated, mating the closure tops 62 with associated guide tools9 and 10 so as to drive the closure top 62 downward against the rod 8and to urge the rod 8 downward into the bone screw channel 153.Preferably, the translation nut 202 of the multi-purpose installationtool 12 is rotated in a clockwise direction, translating the sleeve 204and block 218 downwardly slightly in advance or substantially concurrentwith the advancement of the closure tops 62, providing additionalmechanical advantage for the block flat surface 222 against the rod 8.

With reference to FIG. 43 , at the bottom of the guide tool 9 or 10, theclosure top mating structure 181 engages and begins to mate with theguide and advancement structure 183 on the respective bone screw 4 andcontinued rotation of the tool 302 drives the rod 8 downward and intoengagement with the upper part of the bone screw shank 154, so as tosnug against and frictionally lock the shank 148 in position relative tothe bone screw head 146.

Once all of the closure tops 62 are in final seated position inrespective bone screws 4 and the surgeon is satisfied with the positionof all of the elements, such as is illustrated in FIG. 43 , any and allmulti-purpose installation tools 12 are removed by rotating the nut 202counter-clockwise followed by sliding the sleeve 204 off of the guidetool 9 and 10 and out of the incision 350. Thereafter, each of the guidetools 9 and 10 are now removed by rotating each guide tools 9 and 10ninety degrees so that the recesses 116 straddle the rod 8 to allow theattachment structure 72 or 124 to disengage from the receiver portion145 on the bone screw 4. The guide tool 9 or 10 is then pulled axiallyupward away from the bone screw 4, along the tool 302 and then out ofthe incision 350.

The antitorque tool 300 is mounted over each closure top installationtool 302, utilizing the tool 302 as a guide for re-entry through theincision 350. The antitorque tool 300 is slid along the tool 302 untilthe bridges 310 straddle the rod 8, preventing axial rotation of thetool 300. As shown in FIG. 46 , the closure top installation tool 302 isthen pulled axially upward away from the bone screw 4 and out of theincision 350.

With reference to FIG. 47 , the closure top torquing tool 305 is theninserted into the antitorque tool 300 and engaged with the break-offhead 186. By cooperative use of the tools 300 and 305 a preselectedtorque is manually applied to the break-off head 186 which breaks fromthe closure top 62 as illustrated in FIG. 48 and is thereafter removed,followed by removal of the antitorque tool 300, after which the incision165 is closed.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown. Forexample, it is foreseen that more than one tool could be used to providethe described functions for the multi-purpose installation tool 12.

What is claimed is:
 1. A pivotal bone anchor assembly for securing anelongate rod to a bone of a patient, the pivotal bone anchor assemblycomprising: a receiver having a longitudinal axis, a base, and a pair ofopposed upright arms extending upwardly from the base to define an openchannel therebetween configured to receive the elongate rod, the openchannel extending between a front surface and a back surface of thereceiver and opening onto top surfaces of the upright arms to define atop of the receiver, the upright arms having interior surfaces with adiscontinuous helically wound thread form formed therein and outer sidesurfaces opposite the interior surfaces; and a closure configured to bepositioned within the open channel to secure the elongate rod to thereceiver in a locked configuration, the closure comprising a cylindricalbody having a central axis and an outer surface with a mating continuoushelically wound thread form formed thereon, the thread form of theclosure being configured to resist a tendency toward splaying betweenthe pair of upright arms upon a screwing in of the closure within theopen channel by rotatable engagement with the thread form of thereceiver, the thread form of the closure having a thread pitch, anaxially extending cylindrical root surface, an outer crest surface, anupper thrust surface and a lower clearance surface, the clearancesurface and at least an outer portion of the thrust surface slopingoutwardly and upwardly with respect to the central axis of thecylindrical body of the closure, the outer crest surface having a crestheight defined as the greatest distance between an upper juncture of theouter portion of the thrust surface with a proximal portion of the outercrest surface and a lower juncture of an outer portion of the clearancesurface with a distal portion of the outer crest surface, wherein thecrest height is between 35% and 50% of the thread pitch, wherein whenthe pivotal bone anchor assembly is in the locked configuration, theclosure does not extend over any part of the top surfaces of the uprightarms and the entire lower clearance surface and entire outer crestsurface of the thread form of the closure are spaced apart from thethread form of the receiver.
 2. The pivotal bone anchor assembly ofclaim 1, wherein the outer crest surface includes an axially extendingcylindrical surface.
 3. The pivotal bone anchor assembly of claim 1,wherein the assembly includes the elongate rod.
 4. The pivotal boneanchor assembly of claim 1, wherein the cylindrical body of the closurefurther comprises a top end surface, a bottom end surface, and aplurality of vertical tool engagement surfaces aligned parallel with thecentral axis.
 5. The pivotal bone anchor assembly of claim 1, whereinthe clearance surface slopes outwardly and upwardly at about a 20 degreeangle with respect to a line perpendicular to the central axis.
 6. Thepivotal bone anchor assembly of claim 1, wherein the thrust surfaceincludes a portion sloping outwardly and upwardly at an angle less thanan angle for the clearance surface with respect to a line perpendicularto the central axis.
 7. The pivotal bone anchor assembly of claim 1,wherein the crest height is between 40% and 50% of the thread pitch. 8.A pivotal bone anchor assembly for securing an elongate rod to a bone ofa patient, the pivotal bone anchor assembly comprising: a receiverhaving a longitudinal axis, a base, and a pair of opposed upright armsextending upwardly from the base to define an open channel therebetweenconfigured to receive the elongate rod, the open channel extendingbetween a front surface and a back surface of the receiver and openingonto top surfaces of the upright arms to define a top of the receiver,the upright arms having interior surfaces with a discontinuous helicallywound thread form formed therein and outer side surfaces opposite theinterior surfaces; and a closure configured to be positioned within theopen channel to secure the elongate rod to the receiver in a lockedconfiguration, the closure comprising a cylindrical body having acentral axis and an outer surface with a mating continuous helicallywound thread form formed thereon, the thread form of the closure beingconfigured to resist a tendency toward splaying between the pair ofupright arms upon a screwing in of the closure within the open channelby rotatable engagement with the thread form of the receiver, the threadform of the closure having a thread pitch, an axially extendingcylindrical root surface, an outer crest surface, an upper thrustsurface and a lower clearance surface, the clearance surface slopingoutwardly and upwardly and at least an outer portion of the thrustsurface extending perpendicular with respect to the central axis of thecylindrical body of the closure, the outer crest surface having a crestheight defined as the greatest distance between an upper juncture of theouter portion of the thrust surface with a proximal portion of the outercrest surface and a lower juncture of an outer portion of the clearancesurface with a distal portion of the outer crest surface, wherein thecrest height is between 35% and 50% of the thread pitch, wherein whenthe pivotal bone anchor assembly is in the locked configuration, theclosure does not extend over any part of the top surfaces of the uprightarms and the entire lower clearance surface and entire outer crestsurface of the thread form of the closure are spaced apart from thethread form of the receiver.
 9. The pivotal bone anchor assembly ofclaim 8, wherein the outer crest surface includes an axially extendingcylindrical surface.
 10. The pivotal bone anchor assembly of claim 8,wherein the assembly includes the elongate rod.
 11. The pivotal boneanchor assembly of claim 8, wherein the cylindrical body of the closurefurther comprises a top end surface, a bottom end surface, and aplurality of vertical tool engagement surfaces aligned parallel with thecentral axis.
 12. The pivotal bone anchor assembly of claim 8, whereinthe clearance surface slopes outwardly and upwardly at about a 15 degreeangle with respect to a line perpendicular to the central axis.
 13. Thepivotal bone anchor assembly of claim 12, wherein an outwardly extensionof the slope for the clearance surface and a perpendicular extension ofthe thrust surface intercept at a point lateral to the outer sidesurfaces of the upright arms of the receiver.
 14. The pivotal boneanchor assembly of claim 8, wherein the crest height is between 40% and50% of the thread pitch.